Cluster tool architecture for processing a substrate

ABSTRACT

Embodiments generally provide an apparatus and method for processing substrates using a multi-chamber processing system (e.g., a cluster tool) that has an increased system throughput, increased system reliability, substrates processed in the cluster tool have a more repeatable wafer history, and also the cluster tool has a smaller system footprint. In one embodiment, the cluster tool is adapted to perform a track lithography process in which a substrate is coated with a photosensitive material, is then transferred to a stepper/scanner, which exposes the photosensitive material to some form of radiation to form a pattern in the photosensitive material, which is then removed in a developing process completed in the cluster tool. In track lithography type cluster tools, since the chamber processing times tend to be rather short, and the number of processing steps required to complete a typical track system process is large, a significant portion of the time it takes to process a substrate is taken up by the processes of transferring the substrates in a cluster tool between the various processing chambers. In one embodiment of the cluster tool, the cost of ownership is reduced by grouping substrates together and transferring and processing the substrates in groups of two or more to improve system throughput, and reduces the number of moves a robot has to make to transfer a batch of substrates between the processing chambers, thus reducing wear on the robot and increasing system reliability. In one aspect of the invention, the substrate processing sequence and cluster tool are designed so that the substrate transferring steps performed during the processing sequence are only made to chambers that will perform the next processing step in the processing sequence. Embodiments also provide for a method and apparatus that are used to improve the coater chamber, the developer chamber, the post exposure bake chamber, the chill chamber, and the bake chamber process results. Embodiments also provide for a method and apparatus that are used to increase the reliability of the substrate transfer process to reduce system down time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/458,664, filed Jul. 19, 2006, which is a continuation of Ser. No.11/112,281 that is now U.S. Pat. No. 7,357,842, which claims benefit ofU.S. provisional patent application Ser. No. 60/639,109 filed Dec. 22,2004, which are all herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to an integratedprocessing system containing multiple processing stations and robotsthat are capable of processing multiple substrates in parallel.

2. Description of the Related Art

The process of forming electronic devices is commonly done in amulti-chamber processing system (e.g., a cluster tool) that has thecapability to sequentially process substrates, (e.g., semiconductorwafers) in a controlled processing environment. A typical cluster toolused to deposit (i.e., coat) and develop a photoresist material,commonly known as a track lithography tool, will include a mainframethat houses at least one substrate transfer robot which transportssubstrates between a pod/cassette mounting device and multipleprocessing chambers that are connected to the mainframe. Cluster toolsare often used so that substrates can be processed in a repeatable wayin a controlled processing environment. A controlled processingenvironment has many benefits which include minimizing contamination ofthe substrate surfaces during transfer and during completion of thevarious substrate processing steps. Processing in a controlledenvironment thus reduces the number of generated defects and improvesdevice yield.

The effectiveness of a substrate fabrication process is often measuredby two related and important factors, which are device yield and thecost of ownership (CoO). These factors are important since they directlyaffect the cost to produce an electronic device and thus a devicemanufacturer's competitiveness in the market place. The CoO, whileaffected by a number of factors, is greatly affected by the system andchamber throughput, or simply the number of substrates per hourprocessed using a desired processing sequence. A process sequence isgenerally defined as the sequence of device fabrication steps, orprocess recipe steps, completed in one or more processing chambers inthe cluster tool. A process sequence may generally contain varioussubstrate (or wafer) electronic device fabrication processing steps. Inan effort to reduce CoO, electronic device manufacturers often spend alarge amount of time trying to optimize the process sequence and chamberprocessing time to achieve the greatest substrate throughput possiblegiven the cluster tool architecture limitations and the chamberprocessing times. In track lithography type cluster tools, since thechamber processing times tend to be rather short, (e.g., about a minuteto complete the process) and the number of processing steps required tocomplete a typical process sequence is large, a significant portion ofthe time it takes to complete the processing sequence is taken uptransferring the substrates between the various processing chambers. Atypical track lithography process sequence will generally include thefollowing steps: depositing one or more uniform photoresist (or resist)layers on the surface of a substrate, then transferring the substrateout of the cluster tool to a separate stepper or scanner tool to patternthe substrate surface by exposing the photoresist layer to a photoresistmodifying electromagnetic radiation, and then developing the patternedphotoresist layer. If the substrate throughput in a cluster tool is notrobot limited, the longest process recipe step will generally limit thethroughput of the processing sequence. This is usually not the case intrack lithography process sequences, due to the short processing timesand large number of processing steps. Typical system throughput for theconventional fabrication processes, such as a track lithography toolrunning a typical process, will generally be between 100-120 substratesper hour.

Other important factors in the CoO calculation are the systemreliability and system uptime. These factors are very important to acluster tool's profitability and/or usefulness, since the longer thesystem is unable to process substrates the more money is lost by theuser due to the lost opportunity to process substrates in the clustertool. Therefore, cluster tool users and manufacturers spend a largeamount of time trying to develop reliable processes, reliable hardwareand reliable systems that have increased uptime.

The push in the industry to shrink the size of semiconductor devices toimprove device processing speed and reduce the generation of heat by thedevice, has caused the industry's tolerance to process variability todiminish. Due to the shrinking size of semiconductor devices and theever increasing device performance requirements, the allowablevariability of the device fabrication process uniformity andrepeatability has greatly decreased. To minimize process variability animportant factor in the track lithography processing sequences is theissue of assuring that every substrate run through a cluster tool hasthe same “wafer history.” A substrate's wafer history is generallymonitored and controlled by process engineers to assure that all of thedevice fabrication processing variables that may later affect a device'sperformance are controlled, so that all substrates in the same batch arealways processed the same way. To assure that each substrate has thesame “wafer history” requires that each substrate experiences the samerepeatable substrate processing steps (e.g., consistent coating process,consistent hard bake process, consistent chill process, etc.) and thetiming between the various processing steps is the same for eachsubstrate. Lithography type device fabrication processes can beespecially sensitive to variations in process recipe variables and thetiming between the recipe steps, which directly affects processvariability and ultimately device performance. Therefore, a cluster tooland supporting apparatus capable of performing a process sequence thatminimizes process variability and the variability in the timing betweenprocess steps is needed. Also, a cluster tool and supporting apparatusthat is capable of performing a device fabrication process that deliversa uniform and repeatable process result, while achieving a desiredsubstrate throughput is also needed.

Therefore, there is a need for a system, a method and an apparatus thatcan process a substrate so that it can meet the required deviceperformance goals and increase the system throughput and thus reduce theprocess sequence CoO.

SUMMARY OF THE INVENTION

The present invention generally provides a cluster tool for processing asubstrate, comprising a first processing rack that comprises two or morevertically stacked substrate processing chambers, wherein the firstprocessing rack has a first side and a second side, a second processingrack that comprises two or more vertically stacked substrate processingchambers, wherein the second processing rack has a first side and asecond side, a first robot adapted to access the substrate processingchambers in the first processing rack from the first side, a secondrobot adapted to access the substrate processing chambers in the firstprocessing rack from the second side and the substrate processingchambers in the second processing rack from the first side, and a thirdrobot adapted to access the substrate processing chambers in the secondprocessing rack from the second side.

Embodiments of the invention further provide a cluster tool containingmultiple processing stations and robots that are capable of processingmultiple substrates in parallel. The cluster tool for processingsubstrates, includes a first substrate processing chamber, a secondsubstrate processing chamber, wherein the second substrate processingchamber is a fixed vertical distance from the first substrate processingchamber, a third substrate processing chamber, a fourth substrateprocessing chamber, wherein the fourth substrate processing chamber ispositioned a fixed vertical distance from the third substrate processingchamber, a first robot assembly adapted to access the first substrateprocessing chamber and the second substrate processing chamber, and asecond robot assembly adapted to receive one or more substrates from thefirst substrate processing chamber and one or more substrates from thesecond substrate processing chamber generally simultaneously, and thendeposit the one or more substrates from the first substrate processingchamber in the third substrate processing chamber and the one or moresubstrates from the second substrate processing chamber in the fourthsubstrate processing chamber generally simultaneously.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a first processing rack having aplurality of vertically stacked substrate processing chambers, a secondprocessing rack having a plurality of vertically stacked substrateprocessing chambers, a first robot blade assembly comprise a first robotblade, and a first robot blade actuator, a second robot blade assemblycomprise a second robot blade, a second robot blade actuator, whereinthe first robot blade assembly and a second robot blade assembly arevertically positioned a fixed distance apart and can be separatelyhorizontally positioned by use of the first robot blade actuator or thesecond robot blade actuator, and a robot connected to the first robotblade assembly and the second robot blade assembly, wherein the firstrobot blade assembly and the second robot blade assembly are spaced afixed distance apart and with cooperative motion of the robot areadapted to generally simultaneously access substrates positioned in thetwo vertically stacked substrate processing chambers in the firstprocessing rack or generally simultaneously access substrates positionedin the two vertically stacked substrate processing chambers in thesecond processing rack.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, a first module that comprises a first processingrack that comprises two or more substrate processing chambers stacked ina vertical direction, a second module that comprises a second processingrack that comprises two or more substrate processing chambers stacked ina vertical direction, a first robot assembly adapted to access asubstrate positioned in at least one substrate processing chamber ineach of the first and second processing racks and the cassette, and asecond robot assembly comprises a robot, a first robot blade connectedto the robot, and a second robot blade connected to the robot andpositioned a fixed distance apart from the first robot blade, whereinthe second robot is adapted to access a substrate positioned in at leastone substrate processing chamber in each of the first and secondprocessing racks and the first and second robot blades are adapted togenerally simultaneously transfer, pickup and/or drop-off the substratesin at least two substrate processing chambers in each of the first andsecond processing racks.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a first processing rack containing afirst vertical stack of substrate processing chambers, a first robotadapted to transfer a substrate to a substrate processing chamber in thefirst processing rack, a second processing rack containing a firstvertical stack of substrate processing chambers, a second robot adaptedto transfer a substrate between a substrate processing chamber in thefirst processing rack and a substrate processing chamber in the secondprocessing rack, a controller that is adapted to optimize the movementsof the substrate through the first and second processing rack using thefirst robot or second robot, and a memory, coupled to the controller,the memory comprising a computer-readable medium having acomputer-readable program embodied therein for directing the operationof the cluster tool, the computer-readable program comprising computerinstructions to control the first robot and second robot movementcomprising storing one or more command tasks for the first robot andsecond robot in the memory, review command tasks for first robotretained in the memory, review command tasks for second robot retainedin the memory, and move command tasks from the first robot to the secondrobot or the second robot to the first robot to balance the availabilityof each robot.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, a first processing rack containing a verticalstack of substrate processing chambers and having a first side extendingalong a first direction to access the substrate processing chamberstherethrough, a second processing rack containing a vertical stack ofsubstrate processing chambers and having a first side extending along asecond direction to access the substrate processing chamberstherethrough, wherein the first side and the second side are spaced adistance apart, a first robot having a base that is in a fixed positionbetween the first side of the second processing rack and the first sideof the first processing rack, wherein the first robot is adapted totransfer a substrate to a substrate processing chamber in the firstprocessing rack, the second processing rack and the cassette, a thirdprocessing rack containing a vertical stack of substrate processingchambers and having a first side extending along a third direction toaccess the substrate processing chambers therethrough, a fourthprocessing rack containing a vertical stack of substrate processingchambers and having a first side extending along a fourth direction toaccess the substrate processing chambers therethrough, wherein the thirdside and the fourth side are spaced a distance apart, and a second robotassembly comprises a robot having a base that is in a fixed positionbetween the first side of the third processing rack and the first sideof the fourth processing rack, a first robot blade connected to therobot, and a second robot blade connected to the robot and positioned afixed distance apart from the first robot blade, wherein the first andsecond robot blades are adapted to generally simultaneously transfersubstrates to two chambers in the first, second, third and fourthprocessing racks.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, a first processing chamber that is adapted toperform a first process on a substrate, a second processing chamber thatis adapted to perform a second process on a substrate, wherein the firstprocessing chamber and the second processing chamber are generallyadjacent to each other, a fluid dispensing means that is adapted tofluidly communicate with a first substrate positioned in the firstprocessing chamber and a second substrate positioned in the secondprocessing chamber, wherein the fluid dispensing means comprises a fluidsource, a nozzle that is in fluid communication with the fluid source, afluid delivery means that is adapted to deliver fluid from the fluidsource to the nozzle, a moveable shutter adapted to isolate the firstprocessing chamber from the second processing chamber, and a robotadapted to transfer a substrate between the cassette, the firstprocessing chamber and the second processing chamber.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a first processing rack comprising afirst processing module comprising a first processing chamber that isadapted to perform a first process on a substrate, a second processingchamber that is adapted to perform a second process on a substrate,wherein the first processing chamber and the second processing chamberare generally adjacent to each other, a fluid dispensing means that isadapted to fluidly communicate with a substrate that is being processedin the first processing chamber and the second processing chamber,wherein the fluid dispensing means comprises a fluid source, a nozzlethat is in fluid communication with the fluid source, a fluid deliverymeans that is adapted to deliver fluid from the fluid source to thenozzle, and a moveable shutter adapted to isolate the first processingchamber from the second processing chamber, a second processing modulecomprising a third processing chamber that is adapted to perform a firstprocess on a substrate, a fourth processing chamber that is adapted toperform a second process on a substrate, wherein the first processingchamber and the second processing chamber are generally adjacent to eachother, a fluid dispensing means that is adapted to fluidly communicatewith a substrate that is being processed in the third processing chamberand the fourth processing chamber, wherein the fluid dispensing meanscomprises, a fluid source, a nozzle that is in fluid communication withthe fluid source, a fluid delivery means that is adapted to deliverfluid from the fluid source to the nozzle, and a moveable shutteradapted to isolate the first processing chamber from the secondprocessing chamber, wherein the second processing module is generallyadjacent to the first processing module, and a robot adapted to transfera substrate between the first processing chamber, the second processingchamber, the third processing chamber and the fourth processing chamber.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, a processing module comprising a firstprocessing chamber that is adapted to perform a first process on asubstrate in a processing region, a second processing chamber that isadapted to perform a second process on a substrate in a processingregion, wherein the first processing chamber and the second processingchamber are generally adjacent to each other, a robot that is adapted totransfer and position a substrate in the first processing chamber andsecond processing chamber, wherein the robot comprises a robot blade, anactuator that is adapted to position the robot blade in the first andsecond processing chambers, and a heat exchanging device that is inthermal communication with the robot blade and is adapted to control thetemperature of a substrate positioned thereon, and a system robotadapted to transfer a substrate between the cassette and the firstprocessing chamber.

A cluster tool for processing a substrate, comprising a cassette that isadapted to contain two or more substrates, a processing module thatcomprises a first processing chamber, a second processing chamber thatis generally adjacent to the first processing chamber, a first robotthat is adapted to access a substrate positioned in the first processingchamber and the second processing chamber, wherein the first robotcomprises a first robot blade assembly comprising a first robot blade,and a second robot blade, wherein the first robot blade and the secondrobot blade are spaced a distance apart, a second robot blade assemblycomprising a third robot blade, and a fourth robot blade, wherein thethird robot blade and the fourth robot blade are spaced a distanceapart, wherein the second robot blade assembly and the first robotassembly are spaced a fixed distance apart, and wherein the first robotis adapted to generally simultaneously access the first processingchamber and the second processing chamber.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, a first processing rack that comprises a firstgroup of two or more substrate processing chambers stacked in a verticaldirection, wherein the two or more substrate processing chambers have afirst side extending along a first direction and a second side extendingalong a second direction, a first robot assembly that is adapted toaccess a substrate positioned in at least one substrate processingchamber in the first processing rack from the first side and thecassette, a second processing rack that comprises a second group of twoor more substrate processing chambers stacked in a vertical direction,wherein the two or more substrate processing chambers have a first sideextending along a third direction to access the substrate processingchambers therethrough, and a second robot assembly that comprises arobot, a first robot blade, and a second robot blade, wherein the firstrobot blade and the second robot blade are spaced a distance apart,wherein the second robot assembly is adapted to access a substratepositioned in at least two substrate processing chambers in the firstprocessing rack from the second side generally simultaneously and accessa substrate positioned in at least one substrate processing chamber inthe second processing rack from the third side generally simultaneously.

Embodiments of the invention further provide a cluster tool forprocessing a substrate, comprising a cassette that is adapted to containtwo or more substrates, 12 or more coater/developer chambers, 12 or moreprocessing chambers selected from a group consisting of a bake chamber,a HMDS process chamber or a PEB chamber, and a transferring systemconsisting essentially of a first robot that is adapted to access asubstrate positioned in at least one of the coater/developer chambers,at least one of the processing chambers and the cassette, and a secondrobot assembly that is adapted to access a substrate positioned in atleast one of the coater/developer chambers and at least one of theprocessing chambers, wherein the second robot comprises a robot, a firstrobot blade connected to the robot, and a second robot blade connectedto the robot and positioned a fixed distance apart from the first robotblade, wherein the second robot is adapted to access at least onesubstrate positioned in at least two coater/developer chambers generallysimultaneously and at least one substrate positioned in at least twoprocessing chambers generally simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is an isometric view illustrating a cluster tool according to anembodiment of the invention.

FIG. 1B is a plan view of the processing system illustrated in FIG. 1Awherein the present invention may be used to advantage.

FIG. 1C is another isometric view illustrating a view from the oppositeside shown in FIG. 1A.

FIG. 2A is a plan view that illustrates another embodiment of clustertool that only contains a front end module, which is adapted tocommunicate with a stepper/scanner tool.

FIG. 2B is a plan view that illustrates another embodiment of clustertool that only contains a stand-alone front end module.

FIG. 2C is a plan view that illustrates another embodiment of clustertool that contains a front end module and a central module, wherein thecentral module is adapted to communicate with a stepper/scanner tool.

FIG. 2D is a plan view that illustrates another embodiment of clustertool that contains a front end module, a central module and a rearmodule, wherein the rear module contains a first rear processing rackand a second rear processing rack and the rear robot is adapted tocommunicate with a stepper/scanner tool.

FIG. 2E is a plan view of a processing system illustrated in FIG. 1A,that contains a twin coater/developer chamber 350 and integratedbake/chill chamber 800 wherein the present invention may be used toadvantage.

FIG. 2F is a plan view that illustrates another embodiment of clustertool that contains a front end module and a central processing module,which each contain two processing racks.

FIG. 2G is a plan view that illustrates another embodiment of clustertool that contains a front end module, central processing module and arear processing module, which each contain two processing racks.

FIG. 2H is a plan view that illustrates another embodiment of clustertool that contains a front end module and a central processing module,which each contain two processing racks and a slide assembly to allowthe base of the front end and central robots to translate.

FIG. 2I is a plan view that illustrates another embodiment of clustertool that contains a front end module, central processing module and arear processing module, which each contain two processing racks and twoslide assemblies to allow the base of the front end, central robot andrear robots to translate.

FIG. 3A illustrates one embodiment of a process sequence containingvarious process recipe steps that may be used in conjunction with thevarious embodiments of the cluster tool described herein.

FIG. 3B illustrates another embodiment of a process sequence containingvarious process recipe steps that may be used in conjunction with thevarious embodiments of the cluster tool described herein.

FIG. 3C illustrates another embodiment of a process sequence containingvarious process recipe steps that may be used in conjunction with thevarious embodiments of the cluster tool described herein.

FIG. 4A is a side view that illustrates one embodiment of the front endprocessing rack 52 according to the present invention.

FIG. 4B is a side view that illustrates one embodiment of the firstprocessing rack 152 according to the present invention.

FIG. 4C is a side view that illustrates one embodiment of the secondprocessing rack 154 according to the present invention.

FIG. 4D is a side view that illustrates one embodiment of the rearprocessing rack 202 according to the present invention.

FIG. 4E is a side view that illustrates one embodiment of the first rearprocessing rack 302 according to the present invention.

FIG. 4F is a side view that illustrates one embodiment of the secondrear processing rack 304 according to the present invention.

FIG. 4G is a side view that illustrates one embodiment of the firstprocessing rack 308 according to the present invention.

FIG. 4H is a side view that illustrates one embodiment of the secondprocessing rack 309 according to the present invention.

FIG. 4I is a side view that illustrates one embodiment of the firstcentral processing rack 312 and the first rear processing rack 318,according to the present invention.

FIG. 4J is a side view that illustrates one embodiment of the secondcentral processing rack 314 and the second rear processing rack 319,according to the present invention.

FIG. 4K is a side view that illustrates one embodiment of the firstprocessing rack 322 according to the present invention.

FIG. 5A is a side view that illustrates one embodiment of a coaterchamber wherein the present invention may be used to advantage.

FIG. 5B is a side view that illustrates one embodiment of a coaterchamber wherein the present invention may be used to advantage.

FIG. 5C is a side view that illustrates one embodiment of acoater/developer chamber that contains a showerhead assembly wherein thepresent invention may be used to advantage

FIG. 5D is a side view that illustrates one embodiment of a developerchamber wherein the present invention may be used to advantage.

FIG. 6A is an exploded isometric view of one embodiment of the fluidsource assembly.

FIG. 6B is an exploded isometric view of one embodiment of the fluidsource assembly.

FIG. 7A illustrates a plan view of one embodiment of a coater chamberthat contains a fluid dispense arm that has a single degree of freedom.

FIG. 7B illustrates a plan view of one embodiment of a coater chamberthat contains a fluid dispense arm that has a two degrees of freedom.

FIG. 8A is a side view of one embodiment of the developer chamber 60Bthat contains a developer endpoint detector assembly 1400.

FIG. 8B is process method step used to improve the endpoint detectionprocess described in conjunction with FIG. 8A.

FIG. 8C is a side view of one embodiment of the developer chamber 60Bthat contains a developer endpoint detector assembly 1400.

FIG. 9A is a plan view of a twin coater/developer chamber 350 accordingto the present invention.

FIG. 9B is a plan view of a twin coater/developer chamber 350 accordingto the present invention.

FIG. 10A is a side view that illustrates one embodiment of a chillchamber wherein the present invention may be used to advantage.

FIG. 10B is a side view that illustrates one embodiment of a bakechamber wherein the present invention may be used to advantage.

FIG. 10C is a side view that illustrates one embodiment of a HMDSprocess chamber wherein the present invention may be used to advantage.

FIG. 10D is a side view that illustrates one embodiment of a PostExposure Bake (PEB) chamber wherein the present invention may be used toadvantage.

FIG. 11A is side view that illustrates one embodiment of a plateassembly that may be used to rapidly heat and cool a substrate.

FIG. 12A is a side view of a bake chamber, PEB chamber or HMDS processchamber that contains one embodiment of a process endpoint detectionsystem.

FIG. 12B is a side view of a bake chamber, PEB chamber or HMDS processchamber that contains another embodiment of the process endpointdetection system.

FIG. 12C is process method step used to improve the endpoint detectionprocess described in conjunction with FIGS. 12A-B.

FIG. 13A is a side view of a processing chamber that illustrates oneembodiment of a plate assembly that has improved thermal coupling andreduced contact with the substrate surface.

FIG. 13B is a plan view of the top of the plate assembly shown in FIG.13A.

FIG. 13C is a cross-sectional view of a seed crystal imbedded in thesurface of the plate assembly shown in FIG. 13A.

FIG. 13D is a cross-sectional view of a seed crystal imbedded in thesurface of the plate assembly shown in FIG. 13A, that has a selectivelydeposited layer on its surface.

FIG. 14A is a plan view of a processing system illustrated in FIG. 1Bthat illustrates a transfer path of a substrate through the cluster toolfollowing the process sequence illustrated in FIG. 3A.

FIG. 14B is a plan view of a processing system illustrated in FIG. 2Fthat illustrates a transfer path of a substrate through the cluster toolfollowing the process sequence illustrated in FIG. 3A.

FIG. 15A is an isometric view illustrating one embodiment of a clustertool of the invention that contains a frog-leg robot.

FIG. 15B is a plan view of a processing system illustrated in FIG. 15A,according to the present invention.

FIG. 15C is an isometric view illustrating one embodiment of a frog-legrobot assembly according to the present invention.

FIG. 15D is a plan view of a frog-leg robot assembly of the invention.

FIG. 16A is an isometric view illustrating one embodiment of a dualblade 6-axis articulated robot assembly according to the presentinvention.

FIG. 16B is an isometric view illustrating one embodiment of the dualblade assembly shown in FIG. 16A.

FIG. 16C is an isometric view illustrating one embodiment of the dualblade assembly shown in FIG. 16A.

FIG. 16D is an isometric view illustrating one embodiment of the dualblade assembly shown in FIG. 16A that allows a variable pitch betweenrobot blades.

FIG. 16E illustrates a cross-sectional view of an over/under type dualblade assembly where a single blade has been extended to access asubstrate in a cassette in a pod assembly.

FIG. 16F is an isometric view illustrating one embodiment of a singleblade 6-axis articulated robot assembly wherein the present inventionmay be used to advantage.

FIG. 16G is an isometric view illustrating one embodiment of the singleblade assembly shown in FIG. 16F.

FIG. 16H is an isometric view illustrating one embodiment of a dualblade 6-axis articulated robot assembly and slide assembly according tothe present invention.

FIG. 16I illustrates a cross-sectional view of a dual blade assemblywhere the blades are positioned to transfer substrates from in a pair ofcassettes.

FIG. 17A is an isometric view of one embodiment of a bake chamber, achill chamber and a robot adapted to transfer the substrate between thechambers.

FIG. 17B is an isometric view of one embodiment of a bake chamber, achill chamber and a robot adapted to transfer the substrate between thechambers.

FIG. 17C is an isometric view showing the opposing side of the viewshown in FIG. 17A which illustrates the robot adapted to transfer thesubstrate between the chambers.

FIG. 18A is an isometric view of one embodiment of a bake/chill chamber800.

FIG. 18B is an isometric view showing the opposing side of the viewshown in FIG. 18A which illustrates the robot adapted to transfer thesubstrate between the chambers.

FIG. 19A is a plan view that illustrates another embodiment of clustertool and stepper/scanner tool, where the stepper/scanner is separatedfrom the cluster tool. The stepper/scanner has at least one PEB chamberintegrated into the stepper/scanner.

FIG. 19B illustrates one embodiment of a process sequence containingvarious process recipe steps that may be used in conjunction with thevarious embodiments of the cluster tool shown in FIG. 19A.

FIG. 20A is a side view of the robot illustrated in FIG. 16A which isused in a processing rack configuration that is configured to conform tothe robot's reach.

FIG. 20B is an isometric view another embodiment of a processing rackconfiguration that is adapted to conform to the reach of a robot havinga central mounting point.

FIG. 21A is an isometric view illustrating another embodiment of acluster tool of the invention.

FIG. 21B is a plan view of the processing system illustrated in FIG.21A, according to the present invention.

FIG. 21C is a side view of the processing system illustrated in FIG.21A, according to the present invention.

FIG. 21D is a side view that illustrates one embodiment of the firstprocessing rack 460 of the cluster tool illustrated in FIG. 21A.

FIG. 21E is a side view that illustrates one embodiment of the secondprocessing rack 480 according to the present invention.

FIG. 21F illustrates one embodiment of a process sequence containingvarious process recipe steps that may be used in conjunction with thevarious embodiments of the cluster tool described herein.

FIG. 21G is an isometric view illustrating one embodiment of a robotthat may be adapted to transfer substrates in various embodiments of thecluster tool.

FIG. 21H is an isometric view illustrating one embodiment of a robotshown in FIG. 21G that utilizes a single arm robot. In this view theenclosure components have been removed.

FIG. 21I is an isometric view illustrating one embodiment of ahorizontal motion assembly shown in FIGS. 21G and 21H.

FIG. 22A illustrates an isometric view of processing chambers retainedin a processing rack that have a substrate position error detection andcorrection systems mounted outside each of their openings.

DETAILED DESCRIPTION

The present invention generally provides an apparatus and method forprocessing substrates using a multi-chamber processing system (e.g., acluster tool) that has an increased system throughput, increased systemreliability, more repeatable wafer processing history (or wafer history)within the cluster tool, and also a reduced footprint of the clustertool. In one embodiment, the cluster tool is adapted to perform a tracklithography process in which a substrate is coated with a photosensitivematerial, is then transferred to a stepper/scanner, which exposes thephotosensitive material to some form of radiation to form a pattern inthe photosensitive material, and then certain portions of thephotosensitive material are removed in a developing process completed inthe cluster tool.

FIGS. 1A and 1C are isometric views of one embodiment of a cluster tool10 that illustrates a number of the aspects of the present inventionthat may be used to advantage. One embodiment of the cluster tool 10, asillustrated in FIGS. 1A and 1C, contains a front end module 50, acentral module 150, and a rear module 200. The front end module 50generally contains one or more pod assemblies 105 (e.g., items 105A-D),a front end robot 108 (FIG. 1B), and a front end processing rack 52. Thecentral module 150 will generally contain a first central processingrack 152, a second central processing rack 154, and a central robot 107(FIG. 1B). The rear module 200 will generally contain a rear processingrack 202 and a rear robot 109 (FIG. 1B). In one embodiment, the clustertool 10 contains: a front end robot 108 adapted to access processingchambers in the front end processing rack 52; a central robot 107 thatis adapted to access processing chambers in the front end processingrack 52, the first central processing rack 152, the second centralprocessing rack 154 and/or the rear processing rack 202; and a rearrobot 109 that is adapted to access processing chambers in the rearprocessing rack 202 and in some cases exchange substrates with astepper/scanner 5 (FIG. 1B). In one embodiment, a shuttle robot 110 isadapted to transfer substrates between two or more adjacent processingchambers retained in one or more processing racks (e.g., front endprocessing rack 52, first central processing rack 152, etc.). In oneembodiment, a front end enclosure 104 is used to control the environmentaround the front end robot 108 and between the pod assemblies 105 andfront end processing rack 52.

FIG. 1B illustrates a plan view of one embodiment illustrated in FIG.1A, which contains more detail of possible process chamberconfigurations found in aspects of the invention. Referring to FIG. 1B,the front end module 50 generally contains one or more pod assemblies105, a front end robot 108 and a front end processing rack 52. The oneor more pod assemblies 105, or front-end opening unified pods (FOUPs),are generally adapted to accept one or more cassettes 106 that maycontain one or more substrates “W”, or wafers, that are to be processedin the cluster tool 10. The front end processing rack 52 containsmultiple processing chambers (e.g., bake chamber 90, chill chamber 80,etc.) that are adapted to perform the various processing steps found inthe substrate processing sequence. In one embodiment, the front endrobot 108 is adapted to transfer substrates between a cassette mountedin a pod assembly 105 and between the one or more processing chambersretained in the front end processing rack 52.

The central module 150 generally contains a central robot 107, a firstcentral processing rack 152 and a second central processing rack 154.The first central processing rack 152 and a second central processingrack 154 contain various processing chambers (e.g., coater/developerchamber 60, bake chamber 90, chill chamber 80, etc.) that are adapted toperform the various processing steps found in the substrate processingsequence. In one embodiment, the central robot 107 is adapted totransfer substrates between the front end processing rack 52, the firstcentral processing rack 152, the second central processing rack 154and/or the rear processing rack 202. In one aspect, the central robot107 is positioned in a central location between the first centralprocessing rack 152 and a second central processing rack 154 of thecentral module 150.

The rear module 200 generally contains a rear robot 109 and a rearprocessing rack 202. The rear processing rack 202 generally containsprocessing chambers (e.g., coater/developer chamber 60, bake chamber 90,chill chamber 80, etc.) that are adapted to perform the variousprocessing steps found in the substrate processing sequence. In oneembodiment, the rear robot 109 is adapted to transfer substrates betweenthe rear processing rack 202 and a stepper/scanner 5. Thestepper/scanner 5, which may be purchased from Canon USA, Inc. of SanJose, Calif., Nikon Precision Inc. of Belmont, Calif., or ASML US, Inc.of Tempe, Ariz., is a lithographic projection apparatus used, forexample, in the manufacture of integrated circuits (ICs). Thescanner/stepper tool 5 exposes a photosensitive material (photoresist),deposited on the substrate in the cluster tool, to some form ofelectromagnetic radiation to generate a circuit pattern corresponding toan individual layer of the integrated circuit (IC) device to be formedon the substrate surface.

In one embodiment, a system controller 101 is used to control all of thecomponents and processes performed in the cluster tool 10. The systemcontroller 101 is generally adapted to communicate with thestepper/scanner 5, monitor and control aspects of the processesperformed in the cluster tool 10, and is adapted to control all aspectsof the complete substrate processing sequence. The system controller101, which is typically a microprocessor-based controller, is configuredto receive inputs from a user and/or various sensors in one of theprocessing chambers and appropriately control the processing chambercomponents in accordance with the various inputs and softwareinstructions retained in the controller's memory. The system controller101 generally contains memory and a CPU (not shown) which are utilizedby the controller to retain various programs, process the programs, andexecute the programs when necessary. The memory (not shown) is connectedto the CPU, and may be one or more of a readily available memory, suchas random access memory (RAM), read only memory (ROM), floppy disk, harddisk, or any other form of digital storage, local or remote. Softwareinstructions and data can be coded and stored within the memory forinstructing the CPU. The support circuits (not shown) are also connectedto the CPU for supporting the processor in a conventional manner. Thesupport circuits may include cache, power supplies, clock circuits,input/output circuitry, subsystems, and the like all well known in theart. A program (or computer instructions) readable by the systemcontroller 101 determines which tasks are performable in the processingchamber(s). Preferably, the program is software readable by the systemcontroller 101 and includes instructions to monitor and control theprocess based on defined rules and input data.

FIG. 2A is a plan view that illustrates another embodiment of clustertool 10 that contains a front end module 50 that is attached to thestepper/scanner 5. The front end module 50 in this configuration maycontain a front end robot 108, a front end processing rack 52, and arear robot 109A, which is in communication with the stepper/scanner 5.In this configuration the front end processing rack 52 contains multipleprocessing chambers (e.g., coater/developer chamber 60, bake chamber 90,chill chamber 80, etc.) that are adapted to perform the variousprocessing steps found in the substrate processing sequence. In thisconfiguration the front end robot 108 is adapted to transfer substratesbetween a cassette 106 mounted in a pod assembly 105 and the one or moreprocessing chambers retained in the front end processing rack 52. Also,in this configuration the rear robot 109A is adapted to transfersubstrates between the front end processing rack 52 and astepper/scanner 5. In one embodiment, a shuttle robot 110 is adapted totransfer substrates between two or more adjacent processing chambersretained in one or more processing racks (e.g., front end processingrack 52, first central processing rack 152 (FIG. 1B), etc.). In oneembodiment, the cluster tool 10 contains the front end module 50, butdoes not contain a rear robot 109A and does not interface with thestepper/scanner 5.

FIG. 2B is a plan view that illustrates another embodiment of cluster 10shown in FIG. 2A, that is not adapted to communicate with thestepper/scanner 5. In this configuration, the cluster tool 10 may beused as a stand alone tool to perform a desired process sequenceutilizing the process chambers contained in the front end processingrack 52.

FIG. 2C is a plan view that illustrates yet another embodiment of thecluster tool 10 that contains a front end module 50 and a central module150 that are attached to the stepper/scanner 5 and serviced by the frontend robot 108 and the central robot 107. In one embodiment, the centralrobot 107 is adapted to transfer substrates between the front endprocessing rack 52, the first central processing rack 152, the secondcentral processing rack 154 and/or the stepper/scanner 5. In oneembodiment, a shuttle robot 110 is adapted to transfer substratesbetween two or more adjacent processing chambers retained in one or moreprocessing racks (e.g., front end processing rack 52, first centralprocessing rack 152, etc.).

FIG. 2D is a plan view of yet another embodiment of the cluster tool 10that contains front end module 50, a central module 150, and a rearmodule 300, where the rear processing rack 302 is configured to containa first rear processing rack 302 and a second rear processing rack 304.In this configuration the rear robot 109 may be adapted to transfersubstrates from the first central processing rack 152, the secondcentral processing rack 154, the first rear processing rack 302, thesecond rear processing rack 304, the central robot 107, and/or thestepper/scanner 5. Also, in this configuration the central robot 107 maybe adapted to transfer substrates from the first central processing rack152, the second central processing rack 154, the first rear processingrack 302, the second rear processing rack 304, and/or the rear robot109. In one embodiment, a shuttle robot 110 is adapted to transfersubstrates between two or more adjacent processing chambers retained inone or more processing racks (e.g., front end processing rack 52, firstcentral processing rack 152, etc.).

FIG. 2E illustrates a plan view of one embodiment illustrated in FIG.1B, which contains a twin coater/developer chamber 350 (FIGS. 9A-B)mounted in the second central processing rack 314 (FIG. 4J), that mayadapted to perform a photoresist coat step 520 (FIGS. 3A-C) or a developstep 550 (FIGS. 3A-C) in both of the process chambers 370. Thisconfiguration is advantageous since it allows some of the commoncomponents found in the two process chambers 370 to be shared thusreducing the system cost, complexity and footprint of the tool. FIGS.9A-B, described below, illustrates the various aspects of the twincoater/developer chamber 350. FIG. 2E also contains a bake/chill chamber800 mounted in a first central processing rack 322 (FIG. 4K), that maybe adapted to perform the various bake steps (e.g., post BARC bake step512, PEB step 540, etc. (FIGS. 3A-C)) and chill steps (e.g., post BARCchill step 514, post PEB chill step 542, etc. (FIGS. 3A-C)) in thedesired processing sequence. The bake/chill chamber 800 is describedbelow in conjunction with FIGS. 18A-B.

FIG. 2F is a plan view of yet another embodiment of the cluster tool 10,which contains a front end module 306, and a central module 310. In thisembodiment the front end module 306 may contain a first processing rack308 and a second processing rack 309, and the central module 310 maycontain a first central processing rack 312 and a second centralprocessing rack 314. The front end robot 108 is adapted to transfersubstrates between a cassette 106 mounted in a pod assembly 105, thefirst processing rack 308, the second processing rack 309, the firstcentral processing rack 312, the second central processing rack 314,and/or the central robot 107. The central robot 107 is adapted totransfer substrates between the first processing rack 308, the secondprocessing rack 309, the first central processing rack 312, the secondcentral processing rack 314, the front end robot 108, and/or thestepper/scanner 5. In one embodiment, the front end robot 108, and thecentral robot 107 are articulated robots (described below). In oneembodiment, a shuttle robot 110 is adapted to transfer substratesbetween two or more adjacent processing chambers retained in one or moreprocessing racks (e.g., first processing rack 308, first centralprocessing rack 312, etc.). In one aspect, the front end robot 108 ispositioned in a central location between the first processing rack 308and a second processing rack 309 of the front end module 306. In anotheraspect, the central robot 107 is positioned in a central locationbetween the first central processing rack 312 and a second centralprocessing rack 314 of the central module 310.

FIG. 2G is a plan view of yet another embodiment of the cluster tool 10,which is similar to the embodiment shown in FIG. 2F, with the additionof a rear module 316 which may be attached to a stepper/scanner 5. Inthis embodiment the front end module 306 may contain a first processingrack 308 and a second processing rack 309, the central module 310 maycontain a first central processing rack 312 and a second centralprocessing rack 314, and the rear module 316 may contain a first rearprocessing rack 318 and a second rear processing rack 319. The front endrobot 108 is adapted to transfer substrates between a cassette 106mounted in a pod assembly 105, the first processing rack 308, the secondprocessing rack 309, the first central processing rack 312, the secondcentral processing rack 314, and/or the central robot 107. The centralrobot 107 is adapted to transfer substrates between the first processingrack 308, the second processing rack 309, the first central processingrack 312, the second central processing rack 314, the first rearprocessing rack 318, the second rear processing rack 319, the front endrobot 108, and/or the rear robot 109. The rear robot 109 is adapted totransfer substrates between the first central processing rack 312, thesecond central processing rack 314, the first rear processing rack 318,the second rear processing rack 319, the central robot 107, and/or thestepper/scanner 5. In one embodiment, one or more of the front end robot108, the central robot 107, and the rear robot 109 are articulatedrobots (described below). In one embodiment, a shuttle robot 110 isadapted to transfer substrates between two or more adjacent processingchambers retained in one or more processing racks (e.g., firstprocessing rack 308, first central processing rack 312, etc.). In oneaspect, the rear robot 109 is positioned in a central location betweenthe first rear processing rack 318 and a second rear processing rack 319of the rear module 316.

The embodiments illustrated in FIGS. 2F and 2G may be advantageous sincethe gap formed between the processing racks forms a relatively openspace that will allow maintenance personnel access to cluster toolcomponents that have become inoperable. As shown in FIGS. 2F and 2G, inone aspect of the invention, the gap is as wide as the space between theprocessing racks and as high the height of the processing racks. Sincesystem down-time and system availability are important components indetermining the CoO for a given tool, the ability to easily access andmaintain the cluster tool components have an advantage over other priorart configurations.

FIG. 2H is a plan view of yet another embodiment of the cluster tool 10,which is similar to the embodiment shown in FIG. 2F, with the additionof a slide assembly 714 (FIG. 16H) which allows the base of the frontend robot 108 and the central robot 107 to translate along the length(items A₁ and A₂, respectively) of the cluster tool. This configurationextends the reach of each of the robots and improves the “robotoverlap.” Robot overlap is the ability of a robot to access processingchambers in the processing rack of other modules. While FIG. 2Hillustrates the front end robot 108 and the central robot 107 on asingle slide assembly 714 other embodiments may include having each ofthe robots (Items 107 and 108) on their own slide assembly or only oneof the robots mounted on a slide assembly and the other mounted to thefloor or system frame, without varying from the scope of the invention.

FIG. 2I is a plan view of yet another embodiment of the cluster tool 10,which is similar to the embodiment shown in FIG. 2G, with the additionof two slide assemblies 714A-B (described in FIG. 16H) which allows thebase of the front end robot 108 and the base of the central robot 107and rear robot 109 to translate along the length (items A₁, A₂ and A₃,respectively) of the cluster tool 10. While FIG. 2I illustrates thefront end robot 108 on one slide assembly 714A and the central robot 107and the rear robot 109 on a single slide assembly 714B, otherembodiments may include having one or more of the robots (Items 107, 108and 109) on their own slide assembly (not shown), on a shared slideassembly or all three on a single slide assembly (not shown), withoutvarying from the scope of the invention.

Photolithography Process Sequence

FIG. 3A illustrates one embodiment of a series of method steps 501 thatmay be used to deposit, expose and develop a photoresist material layerformed on a substrate surface. The lithographic process may generallycontain the following: a remove substrate from pod 508A step, a BARCcoat step 510, a post BARC bake step 512, a post BARC chill step 514, aphotoresist coat step 520, a post photoresist coat bake step 522, a postphotoresist chill step 524, an optical edge bead removal (OEBR) step536, an exposure step 538, a post exposure bake (PEB) step 540, a postPEB chill step 542, a develop step 550, and a place in pod step 508B. Inother embodiments, the sequence of the method steps 501 may berearranged, altered, one or more steps may be removed, or two or moresteps may be combined into a single step without varying from the basicscope of the invention.

The remove substrate from pod 508A step is generally defined as theprocess of having the front end robot 108 remove a substrate from acassette 106 resting in one of the pod assemblies 105. A cassette 106,containing one or more substrates “W”, is placed on the pod assembly 105by the user or some external device (not shown) so that the substratescan be processed in the cluster tool 10 by a user-defined substrateprocessing sequence controlled by software retained in the systemcontroller 101.

The BARC coat step 510, or bottom anti-reflective coating process(hereafter BARC), is a step used to deposit an organic material over asurface of the substrate. The BARC layer is typically an organic coatingthat is applied onto the substrate prior to the photoresist layer toabsorb light that otherwise would be reflected from the surface of thesubstrate back into the photoresist during the exposure step 538performed in the stepper/scanner 5. If these reflections are notprevented, optical standing waves will be established in the photoresistlayer, which cause feature size(s) to vary from one location to anotherdepending on the local thickness of the photoresist layer. The BARClayer may also be used to level (or planarize) the substrate surfacetopography, since surface topography variations are invariably presentafter completing multiple electronic device fabrication steps. The BARCmaterial fills around and over the features to create a flatter surfacefor photoresist application and reduces local variations in photoresistthickness. The BARC coat step 510 is typically performed using aconventional spin-on photoresist dispense process in which an amount ofthe BARC material is deposited on the surface of the substrate while thesubstrate is being rotated, which causes a solvent in the BARC materialto evaporate and thus causes the material properties of the depositedBARC material to change. The air flow and exhaust flow rate in the BARCprocessing chamber is often controlled to control the solventvaporization process and the properties of the layer formed on thesubstrate surface.

The post BARC bake step 512, is a step used to assure that all of thesolvent is removed from the deposited BARC layer in the BARC coat step510, and in some cases to promote adhesion of the BARC layer to thesurface of the substrate. The temperature of the post BARC bake step 512is dependent on the type of BARC material deposited on the surface ofthe substrate, but will generally be less than about 250° C. The timerequired to complete the post BARC bake step 512 will depend on thetemperature of the substrate during the post BARC bake step, but willgenerally be less than about 60 seconds.

The post BARC chill step 514, is a step used to assure that the time thesubstrate is at a temperature above ambient temperature is controlled sothat every substrate sees the same time-temperature profile; thusprocess variability is minimized. Variations in the BARC processtime-temperature profile, which is a component of a substrate's waferhistory, can have an effect on the properties of the deposited filmlayer and thus is often controlled to minimize process variability. Thepost BARC chill step 514, is typically used to cool the substrate afterthe post BARC bake step 512 to a temperature at or near ambienttemperature. The time required to complete the post BARC chill step 514will depend on the temperature of the substrate exiting the post BARCbake step, but will generally be less than about 30 seconds.

The photoresist coat step 520 is a step used to deposit a photoresistlayer over a surface of the substrate. The photoresist layer depositedduring the photoresist coat step 520 is typically a light sensitiveorganic coating that is applied onto the substrate and is later exposedin the stepper/scanner 5 to form the patterned features on the surfaceof the substrate. The photoresist coat step 520 is a typically performedusing conventional spin-on photoresist dispense process in which anamount of the photoresist material is deposited on the surface of thesubstrate while the substrate is being rotated, thus causing a solventin the photoresist material to evaporate and the material properties ofthe deposited photoresist layer to change. The air flow and exhaust flowrate in the photoresist processing chamber is controlled to control thesolvent vaporization process and the properties of the layer formed onthe substrate surface. In some cases it may be necessary to control thepartial pressure of the solvent over the substrate surface to controlthe vaporization of the solvent from the photoresist during thephotoresist coat step by controlling the exhaust flow rate and/or byinjecting a solvent near the substrate surface. Referring to FIG. 5A, tocomplete the photoresist coat step 520 the substrate is first positionedon a spin chuck 1033 in a coater chamber 60A. A motor rotates the spinchuck 1033 and substrate while the photoresist is dispensed onto thecenter of the substrate. The rotation imparts an angular torque onto thephotoresist, which forces the photoresist out in a radial direction,ultimately covering the substrate.

The post photoresist coat bake step 522 is a step used to assure thatmost, if not all, of the solvent is removed from the depositedphotoresist layer in the photoresist coat step 520, and in some cases topromote adhesion of the photoresist layer to the BARC layer. Thetemperature of the post photoresist coat bake step 522 is dependent onthe type of photoresist material deposited on the surface of thesubstrate, but will generally be less than about 250° C. The timerequired to complete the post photoresist coat bake step 522 will dependon the temperature of the substrate during the post photoresist bakestep, but will generally be less than about 60 seconds.

The post photoresist chill step 524, is a step used to control the timethe substrate is at a temperature above ambient temperature so thatevery substrate sees the same time-temperature profile and thus processvariability is minimized. Variations in the time-temperature profile canhave an affect on properties of the deposited film layer and thus isoften controlled to minimize process variability. The temperature of thepost photoresist chill step 524, is thus used to cool the substrateafter the post photoresist coat bake step 522 to a temperature at ornear ambient temperature. The time required to complete the postphotoresist chill step 524 will depend on the temperature of thesubstrate exiting the post photoresist bake step, but will generally beless than about 30 seconds.

The optical edge bead removal (OEBR) step 536, is a process used toexpose the deposited light sensitive photoresist layer(s), such as thelayers formed during the photoresist coat step 520 and the BARC layerformed during the BARC coat step 510, to a radiation source (not shown)so that either or both layers can be removed from the edge of thesubstrate and the edge exclusion of the deposited layers can be moreuniformly controlled. The wavelength and intensity of the radiation usedto expose the surface of the substrate will depend on the type of BARCand photoresist layers deposited on the surface of the substrate. AnOEBR tool can be purchased, for example, from USHIO America, Inc.Cypress, Calif.

The exposure step 538 is a lithographic projection step applied by alithographic projection apparatus (e.g., stepper scanner 5) to form apattern which is used to manufacture integrated circuits (ICs). Theexposure step 538 forms a circuit pattern corresponding to an individuallayer of the integrated circuit (IC) device on the substrate surface, byexposing the photosensitive materials, such as, the photoresist layerformed during the photoresist coat step 520 and the BARC layer formedduring the BARC coat step 510 (photoresist) of some form ofelectromagnetic radiation. The stepper/scanner 5, which may be purchasedfrom Cannon, Nikon, or ASML.

The post exposure bake (PEB) step 540 is a step used to heat a substrateimmediately after the exposure step 538 in order to stimulate diffusionof the photoactive compound(s) and reduce the effects of standing wavesin the photoresist layer. For a chemically amplified photoresist, thePEB step also causes a catalyzed chemical reaction that changes thesolubility of the photoresist. The control of the temperature during thePEB is critical to critical dimension (CD) control. The temperature ofthe PEB step 540 is dependent on the type of photoresist materialdeposited on the surface of the substrate, but will generally be lessthan about 250° C. The time required to complete the PEB step 540 willdepend on the temperature of the substrate during the PEB step, but willgenerally be less than about 60 seconds.

The post exposure bake (PEB) chill step 542 is a step used to assurethat the time the substrate is at a temperature above ambienttemperature is controlled, so that every substrate sees the sametime-temperature profile and thus process variability is minimized.Variation in the PEB process time-temperature profile can have an effecton properties of the deposited film layer and thus is often controlledto minimize process variability. The temperature of the post PEB chillstep 542 is thus used to cool the substrate after the PEB step 540 to atemperature at or near ambient temperature. The time required tocomplete the post PEB chill step 542 will depend on the temperature ofthe substrate exiting the PEB step, but will generally be less thanabout 30 seconds.

The develop step 550 is a process in which a solvent is used to cause achemical or physical change to the exposed or unexposed photoresist andBARC layers to expose the pattern formed during the exposure step 538.The develop process may be a spray or immersion or puddle type processthat is used to dispense the developer solvent. In one embodiment of thedevelop step 550, after the solvent has been dispensed on the surface ofthe substrate a rinse step may be performed to rinse the solventmaterial from the surface of the substrate. The rinse solution dispensedon the surface of the substrate may contain deionized water and/or asurfactant.

The insert the substrate in pod step 508B is generally defined as theprocess of having the front end robot 108 return the substrate to acassette 106 resting in one of the pod assemblies 105.

FIG. 3B illustrates another embodiment in which a series of method steps502 that may be used to perform a track lithographic process on thesubstrate surface. The lithographic process in the method steps 502contains all of the steps found in FIG. 3A, but replaces the BARC coatstep 510 and post BARC bake step 512 with a hexamethyldisilazane(hereafter HMDS) processing step 511 and a post HMDS chill step 513. Inother embodiments, the series of the method steps 502 may be rearranged,altered, one or more steps may be removed or two or more steps may becombined into a single step with out varying from the basic scope of theinvention.

The HMDS processing step 511 generally contains the steps of heating thesubstrate to a temperature greater than about 125° C. and exposing thesubstrate to a process gas containing an amount of HMDS vapor for ashort period of time (e.g., <120 seconds) to prepare and dry the surfaceof the substrate to promote adhesion of the photoresist layer depositedlater in the processing sequence. While the use of HMDS vapor isspecifically described above as the chemical used in conjunction withthe HMDS processing step 511, the HMDS processing step 511 is meant tomore generally describe a class of similar processes that may beutilized to prepare and dry the surface of the substrate to promoteadhesion of the photoresist layer. Thus the use of the term HMDS in thisspecification is not intended to be limiting of the scope of theinvention. In some cases the HMDS step is called a “vapor prime” steps.

The post HMDS chill step 513 controls the temperature of the substrateso that all substrates entering the photoresist processing step are atthe same initial processing temperature. Variations in the temperatureof the substrate entering the photoresist coat step 520, can have adramatic affect on properties of the deposited film layer and thus isoften controlled to minimize process variability. The temperature of thepost HMDS chill step 513, is thus used to cool the substrate after theHMDS processing step 511 to a temperature at or near ambienttemperature. The time required to complete the post HMDS chill step 513will depend on the temperature of the substrate exiting the HMDSprocessing step 511, but will generally be less than about 30 seconds.

FIG. 3C illustrates another embodiment of a process sequence, or methodsteps 503, that may be used to perform a track lithographic process onthe substrate. The lithographic process may generally contain a removefrom pod 508A step, a pre-BARC chill step 509, a BARC coat step 510, apost BARC bake step 512, a post BARC chill step 514, a photoresist coatstep 520, a post photoresist coat bake step 522, a post photoresistchill step 524, an anti-reflective top coat step 530, a post top coatbake step 532, a post top coat chill step 534, an optical edge beadremoval (OEBR) step 536, an exposure step 538, a post exposure bake(PEB) step 540, a post PEB chill step 542, a develop step 550, a SAFIER™(Shrink Assist Film for Enhanced Resolution) coat step 551, a postdevelop bake step 552, a post develop chill step 554, and a place in podstep 508B. The lithographic process in the method steps 503 contains allof the steps found in FIG. 3A, and adds the anti-reflective top coatstep 530, the post top coat bake step 532, the post top coat chill step534, a post develop bake step 552, a post develop chill step 554 and theSAFIER™ coat step 551. In other embodiments, the sequence of the methodsteps 503 may be re-arranged, altered, one or more steps may be removedor two or more steps may be combined into a single step with out varyingfrom the basic scope of the invention.

The pre-BARC chill step 509 controls the temperature of the substrate sothat all substrates entering the BARC processing step are at the sameinitial processing temperature. Variations in the temperature of thesubstrate entering the BARC coat step 510, can have a dramatic affect onproperties of the deposited film layer and thus is often controlled tominimize process variability. The temperature of the pre-BARC step 509,is thus used to cool or warm the substrate transferred from the POD to atemperature at or near ambient temperature. The time required tocomplete the pre-BARC chill step 509 will depend on the temperature ofthe substrates in the cassette 106, but will generally be less thanabout 30 seconds.

The anti-reflective top coat step 530 or top anti-reflective coatingprocess (hereafter TARC), is a step used to deposit an organic materialover the photoresist layer deposited during the photoresist coat step520. The TARC layer is typically used to absorb light that otherwisewould be reflected from the surface of the substrate back into thephotoresist during the exposure step 538 performed in thestepper/scanner 5. If these reflections are not prevented, opticalstanding waves will be established in the photoresist layer, which causefeature size to vary from one location to another on the circuitdepending on the local thickness of the photoresist layer. The TARClayer may also be used to level (or planarizing) the substrate surfacetopography, which is invariably present on the device substrate. Theanti-reflective top coat step 530 is a typically performed usingconventional spin-on photoresist dispense process in which an amount ofthe TARC material is deposited on the surface of the substrate while thesubstrate is being rotated which causes a solvent in the TARC materialto evaporate and thus densify the TARC layer. The air flow and exhaustflow rate in the coater chamber 60A is controlled to control the solventvaporization process and the properties of the layer formed on thesubstrate surface.

The post top coat bake step 532 is a step used to assure that all of thesolvent is removed from the deposited TARC layer in the anti-reflectivetop coat step 530. The temperature of the post top coat bake step 532 isdependent on the type of TARC material deposited on the surface of thesubstrate, but will generally be less than about 250° C. The timerequired to complete the post top coat bake step 532 will depend on thetemperature of the process run during the post top coat bake step, butwill generally be less than about 60 seconds.

The post top coat chill step 534 is a step used to control the time thesubstrate is at a temperature above ambient temperature is controlled sothat every substrate sees the same time-temperature profile and thusprocess variability is minimized. Variations in the TARC processtime-temperature profile, which is a component of a substrates waferhistory, can have an affect on the properties of the deposited filmlayer and thus is often controlled to minimize process variability. Thepost top coat chill step 534, is typically used to cool the substrateafter the post top coat bake step 532 to a temperature at or nearambient temperature. The time required to complete the post top coatchill step 534 will depend on the temperature of the substrate exitingthe post top coat bake step 532, but will generally be less than about30 seconds.

The post develop bake step 552 is a step used to assure that all of thedeveloper solvent is removed from the remaining photoresist layer afterthe develop step 550. The temperature of the post develop bake step 552is dependent on the type of photoresist material deposited on thesurface of the substrate, but will generally be less than about 250° C.The time required to complete the post develop bake step 552 will dependon the temperature of the substrate during the post photoresist bakestep, but will generally be less than about 60 seconds.

The post develop chill step 554 is a step used to control and assurethat the time the substrate is at a temperature above ambienttemperature is controlled so that every substrate sees the sametime-temperature profile and thus process variability is minimized.Variations in the develop process time-temperature profile, can have aneffect on properties of the deposited film layer and thus is oftencontrolled to minimize process variability. The temperature of the postdevelop chill step 554, is thus used to cool the substrate after thepost develop bake step 552 to a temperature at or near ambienttemperature. The time required to complete the post develop chill step554 will depend on the temperature of the substrate exiting the postdevelop bake step 552, but will generally be less than about 30 seconds.

The SAFIER™ (Shrink assist film for enhanced resolution) coat step 551,is a process in which a material is deposited over the remainingphotoresist layer after the develop step 550 and then baked in the postdevelop bake step 552. The SAFIER™ process is typically used to causephysical shrinkage of IC trench patterns, vias and contact holes withvery little deterioration of the profile and also improve line edgeroughness (LER). The SAFIER™ coat step 551 is typically performed usingconventional spin-on photoresist dispense process in which an amount ofthe SAFIER™ material is deposited on the surface of the substrate whilethe substrate is being rotated.

Processing Racks

FIGS. 4A-J illustrate side views of one embodiment of a front endprocessing rack 52, a first central processing rack 152, a secondcentral processing rack 154, a rear processing rack 202, a first rearprocessing rack 302, a second rear processing rack 304, a firstprocessing rack 308, a second processing rack 309, a first centralprocessing rack 312, a second central processing rack 314, a first rearprocessing rack 318 and a second rear processing rack 319, that containmultiple substrate processing chambers to perform various aspects of thesubstrate processing sequence. In general, the processing racksillustrated in FIGS. 4A-J may contain one or more process chambers, suchas, one or more coater chambers 60A, one or more developer chambers 60B,one or more chill chambers 80, one or more bake chambers 90, one or morePEB chambers 130, one or more support chambers 65, one or more OEBRchambers 62, one or more twin coater/developer chambers 350, one or morebake/chill chambers 800, and/or one or more HMDS chambers 70, which arefurther described below. The orientation, type, positioning and numberof process chambers shown in the FIGS. 4A-J are not intended to belimiting as to the scope of the invention, but are intended toillustrate the various embodiments of the invention. In one embodiment,as shown in FIGS. 4A-J, the process chambers are stacked vertically, orone chamber is positioned substantially above another chamber, to reducethe footprint of the cluster tool 10. In another embodiment, thechambers stacked vertically so that the processing chambers arepositioned in a horizontally staggered pattern, one chamber ispositioned partially above another chamber, to help make more efficientuse of the processing rack space when one or more chambers are differentphysical sizes. In yet another embodiment, the process chambers may bestaggered vertically, the base of the process chambers do not share acommon plane, and/or are horizontally staggered, where a side of aprocess chamber does not share a common plane with another processchamber. Minimizing the cluster tool footprint is often an importantfactor in developing a cluster tool, since the clean room space, wherethe cluster tool may be installed, is often limited and very expensiveto build and maintain.

FIG. 4A illustrates a side view of the front end processing rack 52 asviewed from outside the cluster tool 10 and in front of the podassemblies 105 when facing the central robot 107 and thus will coincidewith the view shown in FIGS. 1A-B and FIGS. 2A-C. In one embodiment, asshown in FIG. 4A, the front end processing rack 52 contains fourcoater/developer chambers 60 (labeled CD1-4), twelve chill chambers 80(labeled C1-12), six bake chambers 90 (labeled B1-6) and/or six HMDSprocess chambers 70 (labeled P1-6).

FIG. 4B illustrates a side view of the first central processing rack 152as viewed from outside the cluster tool 10 while facing the centralrobot 107 and thus will coincide with the view shown in FIGS. 1A-B andFIGS. 2A-C. In one embodiment, as shown in FIG. 4B, the first centralprocessing rack 152 contains twelve chill chambers 80 (labeled C1-12)and twenty four bake chambers 90 (labeled B1-24).

FIG. 4C illustrates a side view of the second central processing rack154 as viewed from outside the cluster tool 10 while facing the centralrobot 107 and thus will coincide with the view shown in FIGS. 1A-B andFIGS. 2A-C. In one embodiment, as shown in FIG. 4C, the second centralprocessing rack 154 contains four coater/developer chambers 60 (labeledCD1-4) and four support chambers 65 (labeled S1-4). In one embodiment,the four support chambers 65 are replaced with four coater/developerchambers 60.

FIG. 4D illustrates a side view of the rear processing rack 202 asviewed from outside the cluster tool 10 while facing the central robot107 and thus coincides with the views shown in FIGS. 1A-B and FIG. 2B.In one embodiment, as shown in FIG. 4D, the rear processing rack 202contains four coater/developer chambers 60 (labeled CD1-4), eight chillchambers 80 (labeled C1-8), two bake chambers 90 (labeled B1-24), fourOEBR chambers 62 (labeled OEBR1-4), and six PEB chambers 130 (labeledPEB1-6).

FIG. 4E illustrates a side view of the first rear processing rack 302 asviewed from outside the cluster tool 10 while facing the rear robot 109and thus will coincide with the view shown in FIG. 2C. In oneembodiment, as shown in FIG. 4E, the first rear processing rack 302contains four coater/developer chambers 60 (labeled CD1-4), eight chillchambers 80 (labeled C1-8), two bake chambers 90 (labeled B1-24), fourOEBR chambers 62 (labeled OEBR1-4), and six PEB chambers 130 (labeledPEB1-6).

FIG. 4F illustrates a side view of the second rear processing rack 304as viewed from outside the cluster tool 10 while facing the rear robot109 and thus will coincide with the view shown in FIG. 2C. In oneembodiment, as shown in FIG. 4F, the second rear processing rack 304contains four coater/developer chambers 60 (labeled CD1-4) and foursupport chambers 65 (labeled S1-4). In one embodiment, the four supportchambers 65 are replaced with four coater/developer chambers 60.

FIG. 4G illustrates a side view of the first processing rack 308 asviewed from outside the cluster tool 10 while facing the front end robot108 and thus will coincide with the views shown in FIGS. 2F-G. In oneembodiment, as shown in FIG. 4G, the first processing rack 308 containstwelve bake/chill chambers 800 (labeled BC1-12) which are describedbelow in conjunction with FIG. 18.

FIG. 4H illustrates a side view of the second processing rack 309 asviewed from outside the cluster tool 10 while facing the front end robot108 and thus will coincide with the view shown in FIGS. 2F-G. In oneembodiment, as shown in FIG. 4H, the second processing rack 309 containsfour coater/developer chambers 60 (labeled CD1-4) and four supportchambers 65 (labeled S1-4). In one embodiment, the four support chambers65 are replaced with four coater/developer chambers 60.

FIG. 4I illustrates a side view of the first central processing rack312, or the first rear processing rack 318, as viewed from outside thecluster tool 10 while facing the central robot 107, or rear robot 109,and thus will coincide with the views shown in FIGS. 2F-G. In oneembodiment, as shown in FIG. 4I, the first central processing rack 312,or the first rear processing rack 318, contains eight chill chambers 80(labeled C1-8), fourteen bake chambers 90 (labeled B1, B2, B3, B5, B6,B7, etc.), four OEBR chambers 62 (labeled OEBR1-4), and six PEB chambers130 (labeled PEB1-6). In another embodiment, the first centralprocessing rack 312, or the first rear processing rack 318, may bearranged like the configuration illustrated in FIG. 4G, which containstwelve chill chambers 80 and twenty four bake chambers 90.

FIG. 4J illustrates a side view of the second central processing rack314, or the second rear processing rack 319, as viewed from outside thecluster tool 10 while facing the central robot 107 (or rear robot 109)and thus will coincide with the views shown in FIGS. 2F-G. In oneembodiment, as shown in FIG. 4J, the second central processing rack 314,or the second rear processing rack 319, contains four twincoater/developer chambers 350, which contain four pairs of processchambers 370 that may be configured as coater chambers 60A, as developerchambers 60B or combinations thereof.

FIG. 4K illustrates a side view of the first processing rack 322 asviewed from outside the cluster tool 10 while facing the front end robot108 and thus will coincide with the views shown in FIG. 2E. In oneembodiment, as shown in FIG. 4K, the first processing rack 322 containstwelve bake/chill chambers 800 (labeled BC1-12) which are describedbelow in conjunction with FIGS. 18A-B.

Coater/Developer Chamber

The coater/developer chamber 60 is a processing chamber that may beadapted to perform, for example, the BARC coat step 510, the photoresistcoat step 520, the anti-reflective top coat step 530, the develop step550, and/or the SAFIER™ coat step 551, which are shown in FIGS. 3A-C.The coater/developer chamber 60 may generally be configured into twomajor types of chambers, a coater chamber 60A, shown in FIG. 5A, and adeveloper chamber 60B, shown in FIG. 5D (discussed below).

FIG. 5A, is a vertical sectional view of one embodiment of the coaterchamber 60A, that may be adapted to perform the BARC coat step 510, thephotoresist coat step and the anti-reflective top coat step 530. Thecoater chamber 60A may contain an enclosure 1001, a gas flowdistribution system 1040, a coater cup assembly 1003, and a fluiddispense system 1025. The enclosure 1001 generally contains side walls1001A, a base wall 1001B, and a top wall 1001C. The coater cup assembly1003, which contains the processing region 1004 in which the substrate“W” is processed, also contains a cup 1005, a rotatable spin chuck 1034and a lift assembly 1030. The rotatable spin chuck 1034 generallycontains a spin chuck 1033, a shaft 1032 and a rotation motor 1031, anda vacuum source 1015. The spin chuck 1033, which is attached to therotation motor 1031 through the shaft 1032, contains a sealing surface1033A that is adapted to hold the substrate while the substrate is beingrotated. The substrate may be held to the sealing surface 1033A by useof a vacuum generated by the vacuum source 1015. The cup 1005manufactured from a material, such as, a plastic material (e.g., PTFE,PFA, polypropylene, PVDF, etc), a ceramic material, a metal coated witha plastic material (e.g., aluminum or SST coated with either PVDF,Halar, etc.), or other materials that is compatible with the processingfluids delivered from the fluid dispense system 1025. In one embodiment,the rotation motor 1031 is adapted to rotate a 300 mm semiconductorsubstrate between about 1 revolution per minute (RPM) and about 4000RPM.

The lift assembly 1030 generally contains an actuator (not shown), suchas an air cylinder or servomotor, and a guide (not shown), such as alinear ball bearing slide, which are adapted to raise and lower therotatable spin chuck 1034 to a desired position. The lift assembly 1030is thus adapted to position the substrate mounted on the rotatable spinchuck 1034 in the cup 1005 during processing and also lift the substrateabove the top of the cup 1005A to exchange the substrate with anexternal robot (e.g., front end robot 108, central robot 107, rear robot109, etc. which is not shown) positioned outside the enclosure 1001. Arobot blade 611, which is attached to the external robot, enters theenclosure 1001 through the access port 1002 formed in the side wall1001A.

The gas flow distribution system 1040 is adapted to deliver a uniformflow of a gas through the enclosure 1001 and coater cup assembly 1003 tothe exhaust system 1012. In one embodiment the gas flow distributionsystem 1040 is a HEPA filter assembly which generally contains a HEPAfilter 1041 and a filter enclosure 1044. The HEPA filter 1041 and filterenclosure 1044 form a plenum 1042 that allows the gas entering from thegas source 1043 to uniformly flow through the HEPA filter 1041, theenclosure 1001 and the coater cup assembly 1003. In one embodiment, thegas source 1043 is adapted to deliver a gas (e.g., air) at a desiredtemperature and humidity to the processing region 1004.

The fluid dispense system 1025 generally contains one or more fluidsource assemblies 1023 which deliver one or more solution to the surfaceof a substrate mounted on the spin chuck 1033. FIG. 5A illustrates asingle fluid source assembly 1023 which contains a discharge nozzle1024, a supply tube 1026, a pump 1022, a filter 1021, a suck back valve1020 and a fluid source 1019. The support arm actuator 1028 is adaptedto move the discharge nozzle 1024 and the dispense arm 1027 to a desiredposition so that a processing fluid can be dispensed from the dischargenozzle 1024 onto a desired position on the surface of the substrate. Theprocessing fluid may be delivered to the discharge nozzle 1024 by use ofa pump 1022. The pump 1022 removes a processing fluid from the fluidsource 1019 and discharges the processing fluid through the filter 1021,suck back valve 1020 and discharge nozzle 1024 and onto the surface ofthe substrate. The processing solution discharged from the dischargenozzle 1024 may be dispensed onto the substrate “W” while it is rotatedby the spin chuck 1033. The suck back valve 1020 is adapted to draw backan amount of solution from the discharge nozzle 1024 after a desiredamount of processing fluid is dispensed on the substrate to preventdripping of unwanted material on the surface of the substrate. Thedispensed processing solution is spun off the edge of the substrate,collected by inner walls of the cup 1005 and diverted to a drain 1011and ultimately a waste collection system 1010.

Photoresist Thickness Control Chamber

FIG. 5B is a side view of another embodiment of the coater chamber 60A,that may be adapted to perform, for example, the BARC coat step 510, thephotoresist coat step and the anti-reflective top coat step 530. Theembodiment shown in FIG. 5B is adapted to form an enclosure around asubstrate during one or more phases of the deposition steps to controlthe evaporation of the solvent from the surface of the materialdeposited on the substrate surface to improve the thickness uniformityprocess results. Traditionally, thickness uniformity control in atypical spin-on type coating process relies on the control of therotation speed of the substrate and exhaust flow rate to control thevaporization of the uniformity of the final deposited layer. The controlof thickness uniformity is dependent on the air flow across thesubstrate surface during the processing step. The rotation speed duringprocessing is commonly lowered as the diameter of the substrateprocessed in the coater chamber 60A is increased due to the increasedlikelihood of aerodynamic variations across the surface of the substrate(e.g., transition from laminar to turbulent flow). It is believed thatthe aerodynamic variations arise due to the variation in air velocity asa function of substrate radius due to the “pumping effect” caused by themomentum imparted to the air from its interaction with the substratesurface. One issue that arises is that the time it takes to complete thecoat step depends on the ability to spread out and remove the requiredamount of solvent from the thinning photoresist layer, which is afunction of the rotation speed of the substrate. The higher the rotationspeed the shorter the processing time. Therefore, in one embodiment, anenclosure is placed around the substrate to control the environmentaround the surface of the substrate to improve the thickness uniformitycontrol for larger substrate sizes. The improved uniformity control isbelieved to be due to the control of the vaporization of the solvent,since the enclosure formed around the substrate tends to prevent of gasflow across the surface of the substrate, and thus allows thephotoresist to spread out before an appreciable amount of solvent hasevaporated from the photoresist.

The coater chamber 60A in this embodiment generally contains anenclosure 1001, a gas flow distribution system 1040, a coater cupassembly 1003, an processing enclosure assembly 1050, and a fluiddispense system 1025. The embodiment illustrated in FIG. 5B contains anumber of components described above in reference to the coater chamber60A described in FIG. 5A and thus the reference numbers for the same orsimilar components have been reused in FIG. 5B for clarity. It should benoted that the spin chuck 1033 illustrated in FIG. 5A is replaced, inthis embodiment, by the enclosure coater chuck 1056 that has anenclosure coater chuck sealing surface 1056A on which the substraterests and a chuck base region 1056B.

FIG. 5B illustrates the processing enclosure assembly 1050 in theprocessing position. It should be noted that in the “exchange position”(not shown) the enclosure lid 1052 is separated from the chuck baseregion 1056B so that a substrate can be transferred to the enclosurecoater chuck 1056 by use of a robot blade 611 attached to an externalrobot (e.g., front end robot 108, central robot 107, etc.). Theprocessing enclosure assembly 1050 which contains an enclosure lid 1052and the chuck base region 1056B which form a processing region 1051around the substrate so that the processing environment can becontrolled during different phases of the coating process. Theprocessing enclosure assembly 1050 generally contains an enclosure lid1052, the spin chuck 1033, a rotation assembly 1055, and a lift assembly1054. The lift assembly 1054 generally contains a lift actuator 1054Aand lift mounting bracket 1053 which may be attached to a rotationassembly 1055 and a surface of the enclosure 1001. The lift actuator1054A generally contains an actuator (not shown), such as an aircylinder or DC servomotor, and a guide (not shown), such as a linearball bearing slide, that are adapted to raise and lower all of thecomponents contained in the processing enclosure assembly 1050, exceptthe spin chuck 1033.

The rotation assembly 1055 generally contains one or more rotationbearings (not shown) and a housing 1055A that are adapted to allow theenclosure lid 1052 to be rotated as the enclosure coater chuck 1056 isrotated. In one embodiment, the housing 1055A is rotated as the spinchuck 1033 is rotated by the rotation motor 1031, due to frictioncreated by the contact between the enclosure lid 1052 and the chuck baseregion 1056B. The enclosure lid 1052 is attached to the rotationbearings through the lid shaft 1052A. In one embodiment, the contactbetween the enclosure lid 1052 and the chuck base region 1056B isinitiated by the movement of the lift assembly 1030, the lift assembly1054 or both lift assemblies moving together.

In one embodiment, when the enclosure lid 1052 and the chuck base region1056B are in contact, a seal is formed, thus creating an enclosedprocessing environment around the substrate. In one embodiment, thevolume of the processing region 1051 is intended to be rather small tocontrol the vaporization of a solvent from the photoresist on thesurface of the substrate, for example, the gap between the enclosure lid1052 and/or the chuck base region 1056B to the substrate may be about 3mm.

In one embodiment, a photoresist material is delivered to the processingregion 1051 through a tube (not shown) in a clearance hole (not shown)in the lid shaft 1052A, while the enclosure lid 1052 and chuck baseregion 1056B are in contact and the substrate is being rotated at afirst rotational speed. In this step the photoresist will tend to spreadout due to the centrifugal force effects caused by the rotation, but thephotoresist's ability to change properties is restricted due to theformation of a solvent rich vapor over the surface of the substrate.After dispensing the photoresist the enclosure lid 1052 and enclosurecoater chuck 1056 may then be rotated at a second rotational speed untilthe photoresist is thinned to a desired thickness at which time theenclosure lid 1052 is lifted from the surface of the enclosure coaterchuck 1056, to allow the solvent remaining in the photoresist to escapeand thus complete the final solvent vaporization process.

In another embodiment, the photoresist is dispensed using a conventionalextrusion dispense process (e.g., sweep a photoresist dispensing arm(not shown) across a stationary substrate), after which the substrate isenclosed in the processing enclosure assembly 1050 and rotated at adesired speed to achieve a uniform layer of a desired thickness. Afterthe desired thickness has been achieved the enclosure lid 1052 isseparated from the enclosure coater chuck 1056 to allow the completevaporization of the solvent from the photoresist.

In one embodiment of the enclosure lid 1052, a plurality of holes 1052Bare formed in the outer wall of the enclosure lid 1052 to allow theexcess photoresist to exit the processing region 1051 during processing.In this configuration air flow across the surface of the substrate isstill prevented or minimized due to lack of an entry and/or exit pointsfor the flowing air. In this configuration, due to the centrifugal forceacting on the air and photoresist which will cause them to flow out ofthe holes 1052B, the pressure in the processing region 1051 will dropbelow ambient pressure. In one embodiment, the pressure in theprocessing region may be varied during different phases of the processto control the vaporization of the photoresist, by varying the rotationspeed of the substrate, enclosure lid 1052 and enclosure coater chuck1056.

In one embodiment, a solvent rich vapor is injected into the processingregion 1051 through a hole in the lid shaft 1052A during processing tocontrol the final thickness and uniformity of the photoresist layer.

Showerhead Fluid Dispensing System For Solvent/Developer Dispense

In an effort to achieve a uniform and repeatable photoresist layer onthe surface of a substrate, prior art designs have emphasized the designof the coater chamber cup geometry, method of spinning the substrate,varying the air flow through the processing region of the chamber, anddesigning photoresist dispensing hardware that improves process ofdispensing the photoresist layer. These designs achieve one level ofuniformity at varying levels of complexity and cost. Due to the need toreduce CoO and the ever increasing process uniformity requirementsfurther improvement is needed.

FIG. 5C illustrates one embodiment of the coater/developer chamber 60,which contains a fluid distribution device 1070 that is adapted todeliver a fluid to the surface of the substrate during the coatingprocess, to enhance the process uniformity results. In one aspect of theinvention, the fluid is a solvent found in the photoresist layer so thatthe evaporation process can be controlled. In this configuration thefluid distribution device 1070 may be raised and lowered relative to thesubstrate surface by use of a lift assembly 1074 so that an optimum gapbetween the fluid distribution device 1070 and the surface of thesubstrate can be achieved so that the surface of the deposited layer canbe uniformly saturated with the dispensed fluid. In one embodiment, thegap is between about 0.5 mm and about 15 mm. The lift assembly 1074generally contains a lift actuator 1074A and lift mounting bracket 1073which may be attached to a showerhead assembly 1075 and a surface of theenclosure 1001. The lift actuator 1074A generally contains an actuator(not shown), such as an air cylinder or DC servomotor, and a guide (notshown), such as a linear ball bearing slide, that are adapted to raiseand lower all of the components contained in the fluid distributiondevice 1070.

FIG. 5C illustrates the fluid distribution device 1070 in the processingposition. The fluid distribution device 1070 contains a showerheadassembly 1075 which forms a processing region 1071 between the substrateand the fluid distribution device 1070 so that the processingenvironment can be controlled during different phases of the coatingprocess. The fluid distribution device 1070 generally contains ashowerhead assembly 1075, a fluid source 1077 and a lift assembly 1074.

The showerhead assembly 1075 generally contains a showerhead base 1072,a shaft 1072A and a showerhead plate 1072D. The shaft 1072A is attachedto the showerhead base 1072 and has a center hole 1072B formed in theshaft to allow fluid delivered from the fluid source 1077 to flow into aplenum 1072C formed within the showerhead base 1072. The showerheadplate 1072D, which is attached to the showerhead base 1072, contains aplurality of holes 1072F formed therein that connect the plenum 1072C,and thus the fluid source 1077, to the lower surface 1072E of theshowerhead plate 1072D. During processing, a processing fluid isdispensed from the fluid source 1077 into the center hole 1072B, whereit enters the plenum 1072C and then flows through the plurality of holes1072F and into the processing region 1071 formed between the substrateand the lower surface 1072E. In one embodiment, the hole size, number ofholes and distribution of the plurality of holes 1072F across theshowerhead plate 1072D are designed to uniformly deliver the processingfluid to the processing region 1071. In another embodiment, the holesize, number of holes and distribution of the plurality of holes 1072Facross the showerhead plate 1072D are unevenly spaced across theshowerhead plate 1072D to deliver a desired non-uniform distribution ofa processing fluid to the processing region 1071. A non-uniform patternmay be useful to correct the thickness variations caused by aerodynamicor other effects that may cause thickness variations in the depositedphotoresist layer.

In one embodiment, the showerhead assembly 1075 contains a motor 1072Gand a rotary seal 1072H that are adapted to rotate and deliver aprocessing fluid to the showerhead assembly 1075 during processing. Therotary seal 1072H may be a dynamic lip seal, or other similar devicethat are well known in the art.

Photoresist Nozzle Rinse System

FIGS. 6A-B are isometric views that illustrate one embodiment of a fluidsource assembly 1023, described above, that also contains anencapsulating vessel assembly 1096. To reduce the possibility ofcontamination of the discharge nozzle 1024, to try to prevent theprocessing fluid in the supply tube 1026 from drying out, and/or toclean various components of the fluid source assembly 1023 (e.g.,discharge nozzle 1024, supply tube outlet 1026A, etc.), during idletimes or between processing steps the discharge nozzle 1024 ispositioned over the vessel opening 1095A (see FIG. 6A) to form acontrolled region in the environment region 1099. This configuration maybe advantageous where the processing fluid, such as photoresist, isused, since it can easily dry and flake causing particle problems as thedischarge nozzle 1024 is brought over the substrate surface insubsequent processing steps. In one embodiment, the discharge nozzle1024, as shown in FIGS. 6A-B, contains a nozzle body 1024A that isconfigured to hold and support the supply tube 1026 so that theprocessing fluid can be cleanly and repeatably dispensed through thesupply tube outlet 1026A.

FIG. 6A illustrates a configuration where the discharge nozzle 1024 isseparated from the encapsulating vessel assembly 1096 so that it can berotated to dispense the processing fluid on the surface of thesubstrate. The encapsulating vessel assembly 1096 generally contains oneor more rinse nozzles 1090, a vessel 1095, a drain 1094, and a vesselopening 1095A. The rinse nozzles 1090, which are connected to the tubing1090A, are in communication with one or more fluid delivery sources 1093(two are shown in FIGS. 6A-B see items 1093A-B). The drain 1094 isgenerally connected to a waste collection system 1094A

Referring to FIG. 6B, in an effort to reduce contamination of thesubstrate during processing the discharge nozzle 1024 and supply tubeoutlet 1026A are cleaned by use of one or more rinse nozzles 1090 thatare attached to the fluid delivery sources 1093 which can deliver one ormore cleaning solutions to the nozzles. In one embodiment, the cleaningsolution is a solvent that can remove leftover photoresist leftoverafter completing a dispense process. The number and orientation of thenozzles may be arranged so that all sides and surfaces of the dischargenozzle 1024 and supply tube outlet 1026A are cleaned. After cleaning theremaining vapors retained in the environment region 1099 of the vessel1095 may also be useful to prevent the processing fluid(s) retained inthe supply tube 1026 from drying out.

Point of Use Photo Resists Temperature Control

To assure a uniform and repeatable coating process the dispensedphotoresist temperature is often tightly controlled since the propertiesand process results can be greatly affected by the temperature ofdispensed photoresist. The optimum dispense temperature may vary fromone photoresist to another. Therefore, since the coater chamber 60A maycontain multiple fluid source assemblies 1023 to run different processrecipes containing different photoresist materials, the temperature ofthe fluid source assemblies 1023 will each need to be independentlycontrolled to assure desirable process results are consistentlyachieved. Embodiments of the invention provide various hardware andmethods for controlling the temperature of a photoresist before it isdispensed on the surface of a substrate during a coat or developprocess.

In one embodiment, as shown in FIGS. 6A and 6B, the discharge nozzle1024 contains a heat exchanging device 1097 that is adapted to heatand/or cool the nozzle body 1024A, the supply tube 1026 and theprocessing fluid contained in the supply tube 1026. In one embodiment,the heat exchanging device is a resistive heater that is adapted tocontrol the temperature of the processing fluid. In another embodiment,the heat exchanging device 1097 is a fluid heat exchanger that isadapted to control the temperature of the processing fluid by use of afluid temperature controlling device (not shown) that causes a workingfluid to flow through the fluid heat exchanger to control thetemperature of the processing fluid. In another embodiment, the heatexchanging device is a thermoelectric device that is adapted to heat orcool the processing fluid. While FIGS. 6A and 6B show the heatexchanging device 1097 in communication with the nozzle body 1024A,other embodiments of the invention may include configurations where theheat exchanging device 1097 is in contact with the supply tube 1026and/or the nozzle body 1024A to effectively control the temperature ofthe processing fluid. In one embodiment, a length of the supply tube1026 is temperature controlled by use of a second heat exchanger 1097Ato assure that all of the volume of the dispensed processing fluidretained in the supply tube inner volume 1026B will be dispensed on thesurface of the substrate during the next process step is at a desiredtemperature. The second heat exchanger 1097A may be an electric heater,a thermoelectric device and/or a fluid heat exchanging device, asdescribed above.

In one embodiment, the encapsulating vessel assembly 1096 is temperaturecontrolled to assure that the temperature of the nozzle body 1024A andprocessing fluid in the supply tube 1026 are maintained at a consistenttemperature when the discharge nozzle 1024 is positioned over the vesselopening 1095A (see FIG. 6B). Referring to FIGS. 6A-B, the vessel 1095can be heated or cooled by use of a vessel heat exchanging device 1098that is attached to the walls of the vessel 1095. The vessel heatexchanging device 1098 may be an electric heater, a thermoelectricdevice and/or a fluid heat exchanging device, as described above, whichin conjunction with the system controller 101 is used to thus controlthe temperature of the vessel 1095.

In one embodiment, the temperature of the rinse nozzles 1090 andconnected to the tubing 1090A are temperature controlled to assure thatthe cleaning solution sprayed on the discharge nozzle 1024 and supplytube outlet 1026A are at desired temperature so the processing fluid inthe supply tube 1026 is not heated or cooled during the clean process.

Coater Nozzle Placement System

To assure uniform and repeatable process results the position where thephotoresist material is dispensed on the substrate surface is preferablytightly controlled. The uniformity of the deposited photoresist layercan be affected by the position on the substrate surface at which thephotoresist is dispensed. Therefore, it is common for the dispense arm1027 position to be accurately controlled by use of an often expensivesupport arm actuator 1028 that is capable of precisely positioning thedischarge nozzle 1024. An issue arises in that it is common for coaterchambers 60A to have multiple discharge nozzles 1024 to dispensemultiple different photoresist materials, which greatly increases thecost and complexity of the coater chamber 60A, due to the need toaccurately or precisely control many dispense arms 1027. Therefore,various embodiments of the invention provide an apparatus and methodthat utilizes a single dispense arm 1027 that can be easily calibratedsince there is only one arm to calibrate and also accurately control. Inthis configuration the multiple discharge nozzles 1024 found in thevarious fluid source assemblies 1023 are exchanged with the singledispense arm 1192 by use of shuttle assembly 1180 (FIG. 7A). In oneembodiment, a dispense arm 1192 is adapted so that only one degree offreedom (e.g., a single linear direction (z-direction)) needs to becontrolled. This configuration thus allows a more accurate and arepeatable control of the discharge nozzle 1024 position and reduces armcomplexity, system cost, possible substrate scrap, and the need forcalibration.

FIG. 7A is a plan view of one embodiment of a dispense arm system 1170found in a coater chamber 60A, that utilizes a dispense arm 1192 thathas a single degree of freedom. In this configuration the dispense armsystem 1170 will generally contain a dispense arm assembly 1190, ashuttle assembly 1180, and a carrier assembly 1160. The dispense armassembly 1190 generally contains a dispense arm 1192, a nozzle mountingposition 1193 formed in or on the dispense arm 1192, and an actuator1191. In one embodiment, a nozzle retaining feature 1194 is adapted tograsp the discharge nozzle 1024 when it is deposited on the nozzlemounting position 1193 by the shuttle assembly 1180. The nozzleretaining feature 1194 may be a spring loaded or pneumatically actuateddevice which grasps or interlocks with features on the discharge nozzle.The actuator 1191 is, for example, an air cylinder or other device thatis able to raise and lower the dispense arm 1192. In one embodiment, theactuator 1191 also contains a linear guide (not shown) which helps tocontrol the placement or movement of the dispense arm 1192 as it ismoved from one position to the other.

The carrier assembly 1160 generally contains a nozzle support 1161, twoor more fluid source assembly 1023 that contains a discharge nozzle 1024and supply tube 1026 (six discharge nozzle 1024 and fluid sourceassemblies 1023 are shown) and a rotary actuator (not shown). The rotaryactuator is adapted to rotate the nozzle support 1161 and all of thedischarge nozzles 1024 and their associated supply tube 1026 to adesired position by use of commands from the system controller 101.

The shuttle assembly 1180 is adapted to pick up a discharge nozzle 1024from the carrier assembly 1160 and then rotate to transfer the dischargenozzle 1024 to the nozzle mounting position 1193 on the dispense arm1192. The shuffle assembly 1180 generally contains an actuator assembly1181, a shuttle arm 1182 and a nozzle transfer feature 1183. The nozzletransfer feature 1183 is adapted to engage with or grasp the dischargenozzle 1024 so that it can be removed from the carrier assembly 1160 andtransferred to nozzle mounting position 1193 and then returned from thenozzle mounting position 1193 to the carrier assembly 1160 after theprocess is complete. The actuator assembly 1181 generally contains oneor more actuators that are adapted to raise and lower the shuttleassembly 1180 and rotate the shuttle arm 1182 to a desired position. Theactuator assembly 1181 may contain, for example, one or more of thefollowing devices to complete the lifting task tasks: an air cylinder,DC servo motor attached to a lead screw, a DC servo linear motor. Theactuator assembly 1181 may also contain, for example, one or more of thefollowing devices to complete the rotational tasks: an air cylinder, astepper motor or a DC servo motor.

In operation the shuttle arm 1182 rotates from its home position (seeitem “A” in FIG. 7A) to a position over the carrier assembly 1160 andthen moves vertically until it reaches a nozzle pickup position (notshown). The carrier assembly 1160 then rotates (see item “B”) so thatthe discharge nozzle 1024 engages with the nozzle transfer feature 1183.The shuttle arm 1182 then moves vertically to separate the dischargenozzle 1024 from the carrier assembly 1160 and then rotates until thedischarge nozzle 1024 is positioned over the nozzle mounting position1193 in dispense arm 1192. The shuttle arm 1182 moves vertically untilit deposits the discharge nozzle 1024 on the nozzle mounting position1193. The shuttle arm 1182 then moves vertically and then rotates backto the home position (see item “A”). The actuator 1191 in the dispensearm assembly 1190 then moves the discharge nozzle to a desired positionover the surface of the substrate (see item “W”), so that the substrateprocessing step can begin. To remove the discharge nozzle 1024 the stepsare followed in reverse.

FIG. 7B illustrates another embodiment of the dispense arm system 1170,where the dispense arm assembly 1190 has two degrees of freedom, suchas, a rotational degree of freedom, or a single linear degree of freedom(x-direction), and a vertical degree of freedom (z-direction). Thedispense arm assembly 1190, which was a part of the embodiment shown inFIG. 7A, is not a part of the dispense arm system 1170 illustrated inFIG. 7B, thus reducing the complexity of the coater chamber 60A. In oneembodiment, a nozzle retaining feature 1184 is adapted to grasp orretain the discharge nozzle 1024 when it is positioned in the nozzletransfer feature 1183. FIG. 7B also illustrates another possibleconfiguration of the nozzle retaining feature 1184 that may be usefulfor holding and transferring the discharge nozzle 1024. In operation theshuttle arm 1182 rotates from its home position (see item “A” in FIG.7B) to a position over the carrier assembly 1160 and then movesvertically until it reaches a nozzle pickup position (not shown). Thecarrier assembly 1160 then rotates (see item “B”) so that the dischargenozzle 1024 engages with the nozzle transfer feature 1183. The shuttlearm 1182 then moves vertically to separate the discharge nozzle 1024from the carrier assembly 1160 and then rotates until the dischargenozzle 1024 is positioned over a desired position over the surface ofthe substrate. The shuttle arm 1182 moves vertically until it reaches adesired position over the surface of the substrate (se item “W”), sothat the substrate processing step can begin. To remove the dischargenozzle 1024 the steps are followed in reverse.

In one embodiment, the carrier assembly 1160 may contain a plurality ofencapsulating vessel assemblies 1096 (not shown in FIGS. 7A-B (see FIGS.6A-B)) which are temperature controlled to assure that the temperatureof the nozzle body 1024A and processing fluid in the supply tube 1026are maintained at a consistent temperature while they are waiting to betransferred to the shuttle assembly 1180 and brought over the surface ofthe substrate.

Developer Chamber

Referring to FIG. 5D, which is a side view of one embodiment of thedeveloper chamber 60B, that may be adapted to perform, for example, thedevelop step 550, and the SAFIER™ coat step 551. In one embodiment, thedeveloper chamber 60B generally contains all of the components containedin the coater chamber 60A and thus some components of the developerchamber 60B that are the same or similar to those described withreference to the developer chamber 60B, have the same numbers.Accordingly, like numbers have been used where appropriate.

In one embodiment, the developer chamber 60B contains a fluiddistribution device 1070, described above, is adapted to deliver auniform flow of a developer processing fluid to the surface of thesubstrate during the developing process. In one embodiment, the holesize, number of holes and distribution of the plurality of holes 1072Fare designed to uniformly deliver the developer processing fluid to theprocessing region 1071 formed between the substrate and the bottomsurface of the fluid distribution device 1070. In another embodiment,the hole size, number of holes and distribution of the plurality ofholes 1072F are designed to deliver a non-uniform distribution of adeveloper processing fluid to the processing region 1071 formed betweenthe substrate and the bottom surface of the fluid distribution device1070.

Developer Endpoint Detection Mechanism

FIG. 8A is a side view of one embodiment of the developer chamber 60Bthat contains a developer endpoint detector assembly 1400. The developerendpoint detector assembly 1400 uses a laser and one or more detectorsto perform a scatterometry type technique to determine the endpoint ofthe develop step 550. In one embodiment, a single wavelength of emittedradiation, or beam, (see item “A”) from a laser 1401 impinges on thesurface of the substrate, having an exposed photoresist layer thereon,at an angle that is less than normal to the surface of the substrate.The beam “A” is reflected from the surface of the substrate and theintensity of the reflected radiation “B” is detected by a detector 1410.In one embodiment, the detector 1410 is oriented to receive the primaryreflection from the surface and thus is aligned with the incident beam(e.g., same angle relative to the surface and the same direction). Dueto the interference between the impinging beam and the pattern formed inthe photoresist during the exposure step 538, the intensity of thedetected radiation will vary as the develop step 550 progresses. Thevariation in the intensity of the reflected radiation is created whenthe developer dissolves the soluble portions of the photoresist duringthe develop step 550, thus causing a “grating” type pattern to emergewhich thus increasingly interferes with the impinging beam. Therefore,the interference with the photoresist pattern causes scattering of theimpinging beam, which causes a reduction in the main reflection that isdetected. In one embodiment, the endpoint is detected when the change inthe reflected intensity measured by the detector 1410 asymptoticallyapproaches zero.

The area on the surface of the substrate, on which the beam emitted fromthe laser 1401 is projected, is defined as the detection area. In oneembodiment, the size of the detection area is varied or controlled sothat the amount of noise contained in the detected signal is minimized.Noise in the detected signal can be generated due to the variation inthe pattern topology seen by the detection area during processing.

In one embodiment, a tunable laser is used in place of a singlewavelength laser to more easily detect the change in the sharpness ofthe photoresist pattern as the develop process progresses. The amount ofinterference will depend on the size of the formed “grating” and thewavelength of the incident radiation. In another embodiment, a pluralityof detectors (see items 1410-1412) that are able to detect the primaryreflection and the amount of scattered radiation to help determine thedevelop endpoint. In another embodiment a CCD (charge coupled device)array is used to monitor the scattering and shift in intensity of thereflected radiation. In one embodiment, to prevent noise generated fromthe reflection of emitted radiation from the processing fluid retainedon the substrate surface during processing, a slit may be used toprevent the reflection from reaching the detector.

For product substrates, where typically there is already a pattern onthe surface of the substrate, the steps shown in FIG. 8B may be used.The process steps include measuring the initial intensity of thescattered radiation prior to performing the develop step 550 (item#1480). The intensity is then measured during the develop process andcompared to the initial data so that the contribution from the patternpresent on the substrate surface (item #1482). This method may only beneeded if the photoresist profile is desired. If noting that theintensity changes over the develop processing period are all that isdesired, then the use of a single wavelength is all that is needed andthe information regarding the underlying scattering generally is notneeded.

If detailed knowledge of the pattern is required, then active correction(item#1484 in FIG. 8C) for the possibly variable refraction at thedeveloper surface is needed. The active correction adjusts for thevariation in the developer fluid surface due to external vibrations, andworks by having multiple small mirrors (items 1425-27) that adjust inposition to compensate for the change in angle. FIG. 8C illustrates onesuch mirror, with knowledge of the change in the refraction of theincident beam “A” obtained via input from a perpendicular beam (item“C”), also shown. In particular, as the surface of the developer fluidmomentarily deviates from flat and level, the normal reflection of thelaser beam (item “C”) from laser 1451 is detected in detector 1453, byuse of beam splitter 1452. In this configuration the detector 1453 canbe a CCD array that is able to sense the change in angle of thereflected beam due to the change in the angle with which the beam “C”strikes the surface of the developer fluid. The system controller 101 inconjunction with the CCD array is able to detect a change in theposition of the peak intensity on the CCD array and thus know how muchthe reflection angle has changed so that the angle of the active mirrors1425-1427 can be adjusted and thus the position of the reflected beam“B” can be sent to one or more of the detectors 1410-1412. Momentarydeviation in the spatial position of this reflection should correlatewell with deviations in the developer fluid surface. Therefore, by useof a suitable control system the detected variation in position of thereflected beam, through the use of actively positioned mirrors (items1425-1427), a spatial correction to the reflected beams can be made.

The active mirrors 1425-1427 can be small and compact, such as used onthe micromirror chip available from TI in Dallas, Tex. They are shownmore widely separated in FIG. 8C for clarity. The active mirrors aredesigned to compensate for variation the developer surface leading tobeam deflection as described above.

Twin Coater and Developer Chambers

FIGS. 9A-B are plan views of one embodiment of a twin coater/developerchamber 350 that contains two separate process chambers 370 and acentral region 395. This configuration is advantageous since it allowssome common components in the two chambers to be shared, thus increasingsystem reliability and reducing the system cost, complexity andfootprint of the cluster tool. In one embodiment, the process chamber370 generally contains all of the processing components described abovein conjunction with the coater chamber 60A or developer chamber 60B,except the two chambers are adapted to share a fluid dispense system1025. The central region 395 contains a shutter 380 and a plurality ofnozzles 391 that are contained in a nozzle holder assembly 390. As notedabove the fluid dispense system 1025 used in the coater or developerchambers may contain one or more fluid source assemblies 1023 whichdeliver one or more processing fluid to the surface of a substratemounted on the spin chuck 1033. Each nozzle 391, contained in the fluidsource assemblies 1023, is typically connected to a supply tube 1026, apump 1022, a filter 1021, a suck back valve 1020 and a fluid source1019, and is adapted to dispense a single type of processing fluid.Therefore, each fluid source assembly 1023 can be used in either theleft or right process chambers 370, thus reducing the redundancyrequired to in each processing chamber. While FIGS. 9A-B illustrates aconfiguration where the nozzle holder assembly 390 contains five nozzles391, in other embodiments the nozzle holder assembly 390 may contain alesser number of nozzles or a greater number of nozzles without varyingform the basic scope of the invention.

FIG. 9A is a plan view of the twin coater/developer chamber 350 wherethe nozzle arm assembly 360 is positioned over the right process chamber370 to dispense a processing fluid on a substrate “W” retained on thespin chuck 1033. The nozzle arm assembly 360 may contain an arm 362 andnozzle holding mechanism 364. The nozzle arm assembly 360 is attached toan actuator 363 that is adapted to transfer and position the nozzle armassembly 360 in any position along the guide mechanism 361. In oneembodiment, the actuator is adapted to move the nozzle arm assembly 360vertically to correctly position the nozzle 391 over the substrateduring processing and also enable the nozzle holding mechanism 364 topick-up and drop-off the nozzles 391 from the nozzle holder assembly390. The system controller 101 is adapted to control the position of thenozzle arm assembly 360 so that the nozzle holding mechanism 364 canpick-up and drop-off nozzles 391 from the nozzle holder assembly 390. Ashutter 380 is adapted to move vertically to close and isolate oneprocess chamber 370 from the central region 395 and thus the otherprocess chamber 370 during processing to prevent cross contamination ofthe substrates during processing. In one aspect, the shutter 380 isadapted to sealably isolate one process chamber 370 from the centralregion 395 and thus the other process chamber 370 during processing.Conventional o-ring and/or other lip seals may be used to allow theshutter to sealably isolate the two processing chambers.

FIG. 9B is a plan view of the twin coater/developer chamber 350 wherethe nozzle arm assembly 360 is positioned over the left process chamber370 to dispense a processing fluid on a substrate retained on the spinchuck 1033.

In one embodiment, not shown, the twin coater/developer chamber 350contains two nozzle arm assemblies 360 which are adapted to access thenozzles 391 in the central region 395 and position a nozzle over thesurface of the substrate. In this configuration each process chambercould process two substrates using the same processing fluid by sharingthe pump and dispensing from two different nozzles 391, or two differentprocessing fluids could be dispensed in each of the chambers.

Chill Chamber

FIG. 10A is a vertical sectional view that illustrates one embodiment ofa chill chamber 80 that may be adapted to perform the post BARC chillstep 514, the post photoresist chill step 524, the post top coat chillstep 534, the post PEB chill step 542 and/or the post develop chill step554. The chill chamber 80 generally contains an enclosure 86, chillplate assembly 83, a support plate 84, and a lift assembly 87. Theenclosure 86 is formed by a plurality of walls (items 86B-D and item 85)which isolate the processes performed in the chill chamber 80 from thesurrounding environment to form a processing region 86A. In one aspectof the invention the enclosure is adapted to thermally isolate andminimize the possibility of atmospheric contamination in the chillchamber 80.

The chill plate assembly 83 generally contains a heat exchanging device83A and a chill plate block 83B. The chill plate block 83B is athermally conductive block of material that is cooled by the heatexchanging device 83A to perform the various chill processes describedabove (e.g., pre-BARC chill step 509, post BARC chill step 514, postphotoresist chill step 524, etc.). The chill plate block 83B isthermally conductive to improve temperature uniformity duringprocessing. In one embodiment, the chill plate block 83B may be madefrom aluminum, graphite, aluminum-nitride, or other thermally conductivematerial. In one embodiment, the chill plate block 83B surface which isin contact with the substrate “W” is coated with a Teflon impregnatedanodized aluminum, silicon carbide or other material that can minimizeparticle generation on the backside of the substrate as it comes incontact with the chill plate block 83B. In one embodiment, the substrate“W” rests on pins (not shown) embedded in the surface of the chill plateblock 83B so that only a small gap is maintained between the substrateand the chill plate block 83B to reduce particle generation. In anotherembodiment, as shown in FIG. 10A, the heat exchanging device 83Aconsists of a plurality of channels 83C formed in a surface of the chillplate block 83B, which are temperature controlled by use of a heatexchanging fluid that continually flows through the channels 83C. Afluid temperature controller (not shown) is adapted to control the heatexchanging fluid and thus the chill plate block 83B temperature. Theheat exchanging fluid may be, for example, a perfluoropolyether (e.g.,Galden®) that is temperature controlled to a temperature between about5° C. and about 20° C. The heat exchanging fluid may also be chilledwater delivered at a desired temperature between about 5° C. to about20° C. The heat exchanging fluid may also be a temperature controlledgas, such as argon or nitrogen.

In one embodiment of the chill plate, the heat exchanging device 83A isadapted to heat and cool the substrate resting on the surface of thechill plate block 83B. This configuration may be advantageous since thetime required to achieve a desired process set point temperature isdependent on the temperature differential between the substrate and thechill plate block 83B. Thus if the chill plate block 83B is set to afixed temperature and it is desired that the substrate be cooled to thatfixed temperature it will take a very long time to cool the last fewdegrees to reach the fixed temperature due to the small temperaturedifferential between the substrate and the chill plate block 83B. Thetime to achieve a desired temperature can be reduced if the temperatureof the chill plate block 83B is actively controlled so that a largetemperature differential is maintained between the substrate and thechill plate block 83B until the substrate temperature is at or near thedesired set point temperature and then the temperature of the chillplate block 83B is adjusted to minimize the amount of undershoot orovershoot in temperature of the substrate. The temperature of the chillplate block 83B is controlled by use of a conventional temperaturesensing device (e.g., thermocouple; (not shown)) that is used inconjunction with the system controller 101 to vary the amount of energyremoved from or delivered to the chill plate block 83B by the heatexchanging device 83A. Thus in this embodiment, the heat exchangingdevice 83A has the ability to both heat and cool the chill plate block83B. In one embodiment, the heat exchanging device 83A is athermoelectric device that is used to cool and/or heat the chill plateblock 83B. In one embodiment, the heat exchanging device 83A is a heatpipe design, described below in conjunction with the PEB chamber 130,which is adapted to heat and cool the substrate. In one embodiment, itmay also be advantageous to minimize the mass and/or increase thethermal conductivity of the chill plate block 83B to improve the abilityto control the substrate temperature.

The support plate 84 is generally a plate that supports the chill plateassembly 83 and insulates it from the base 85. In general the supportplate 84 may be made from a thermally insulating material such as aceramic material (e.g., zirconia, alumina, etc.) to reduce external heatloss or gain.

Referring to FIG. 10A, the lift assembly 87 generally contains a liftbracket 87A, an actuator 87B, a lift pin plate 87C, and three or morelift pins 87D (only two are shown in FIG. 10A), which are adapted toraise and lower the substrate “W” off an extended robot blade (notshown) and place the substrate on the surface of the chill plate block83B once the robot blade has been retracted. The robot blade (not shown)is adapted to enter the chill chamber 80 through an opening 88 in theside wall 86D of the enclosure 86. To prevent substrate to substrateprocess variation and damage to the substrate caused by misalignment ofthe substrate in the chamber the robot is calibrated to pick up and dropoff a substrate from a transfer position, which is typically aligned toa center point between the lift pins. In one embodiment, three liftpins, which move through the lift pin holes 89 in the base 85, supportplate 84, and chill plate assembly 83, are adapted to raise and lowerthe substrate by use of the actuator 87B. The actuator may be an aircylinder or other conventionally available means of raising and loweringthe substrate.

Bake Chamber

FIG. 10B is a side view that illustrates one embodiment of a bakechamber 90 that may be adapted to perform the post BARC bake step 512,the post photoresist coat bake step 522, the post top coat bake step 532and/or the post develop bake step 552. The bake chamber 90 generallycontains an enclosure 96, bake plate assembly 93, a support plate 94,and a lift assembly 97. The enclosure 96 generally contains a pluralityof walls (items 96B-D and element 95) which tend to isolate theprocesses performed in the bake chamber 90 from the surroundingenvironment to form a processing region 96A. In one aspect of theinvention the enclosure is adapted to thermally isolate and minimizecontamination of the bake chamber 90 from the surrounding environment.

The bake plate assembly 93 generally contains a heat exchanging device93A and a bake plate block 93B. The bake plate block 93B is a thermallyconductive block of material that is heated by the heat exchangingdevice 93A to perform the various bake processes described above (e.g.,post BARC bake step 512, post photoresist coat bake step 522, etc.). Thebake plate block 93B is thermally conductive to improve temperatureuniformity during processing. In one embodiment, the bake plate block93B may be made from aluminum, graphite, aluminum-nitride, or otherthermally conductive material. In one embodiment, the bake plate block93B surface which is in contact with the substrate “W” is coated with aTeflon impregnated anodized aluminum, silicon carbide or other materialthat can minimize particle generation on the backside of the substrateas it comes in contact with the bake plate block 93B. In one embodiment,the substrate “W” rests on pins (not shown) embedded in the surface ofthe bake plate block 93B so that only a small gap is maintained betweenthe substrate and the bake plate block 93B to reduce particlegeneration. In one embodiment, the heat exchanging device 93A is athermoelectric device that is used to heat the bake plate block 93B. Inanother embodiment, as shown in FIG. 10B, the heat exchanging device 93Aconsists of a plurality of channels 93C formed in a surface of the bakeplate block 93B, which are temperature controlled by use of a heatexchanging fluid that continually flows through the channels 93C. Afluid temperature controller (not shown) is adapted to control the heatexchanging fluid and thus the bake plate block 93B temperature. The heatexchanging fluid may be, for example, a perfluoropolyether (e.g.,Galden®) that is temperature controlled to a temperature between about30° C. and about 250° C. The heat exchanging fluid may also be atemperature controlled gas, such as argon or nitrogen.

The support plate 94 is generally a plate that supports the bake plateassembly 93 and insulates it from the base 95. In general the supportplate 94 may be made from a thermally insulating material such as aceramic material (e.g., zirconia, alumina, etc.) to reduce external heatloss.

Referring to FIG. 10B, the lift assembly 97 generally contains a liftbracket 97A, an actuator 97B, a lift pin plate 97C, and three or morelift pins 97D (only two are shown in FIG. 10B), which are adapted toraise and lower the substrate “W” off an extended robot blade (notshown) and place the substrate on the surface of the bake plate block93B once the robot blade has been retracted. In one embodiment, threelift pins, which move through the lift pin holes 99 in the base 95,support plate 94, and bake plate assembly 93, are adapted to raise andlower the substrate by use of the actuator 97B. The actuator may be anair cylinder or other conventionally available means of raising andlowering the substrate. The robot blade (not shown) is adapted to enterthe bake chamber 90 through an opening 98 in the side wall 96D of theenclosure 96.

HMDS Chamber

FIG. 10C is a side view that illustrates one embodiment of a HMDSprocess chamber 70 that may be adapted to perform the HMDS processingstep 511. In one embodiment, as shown in FIG. 10C, the HMDS processchamber 70 contains some of the components contained in the bake chamber90 shown in FIG. 10B and thus some components of the HMDS processchamber 70 are the same or similar to those described with reference tothe bake chamber 90, described above. Accordingly, like numbers havebeen used where appropriate.

The HMDS process chamber 70 also contains a lid assembly 75 that is usedto form a sealed processing region 76 in which the processing gas isdelivered to the substrate “W” which is heated by the HMDS bake plateassembly 73. The HMDS bake plate assembly 73 generally contains a heatexchanging device 73A and a HMDS bake plate block 73B. The HMDS bakeplate block 73B is a thermally conductive block of material that isheated by the heat exchanging device 73A to perform the various HMDSprocessing steps described above. The HMDS bake plate block 73B isthermally conductive to improve temperature uniformity duringprocessing. In one embodiment, the HMDS bake plate block 73B may be madefrom aluminum, graphite, aluminum-nitride, or other thermally conductivematerial. In one embodiment, the HMDS bake plate block 73B surface whichis in contact with the substrate “W” is coated with a Teflon impregnatedanodized aluminum, silicon carbide or other material that can minimizeparticle generation on the backside of the substrate as it comes incontact with the HMDS bake plate block 73B. In one embodiment, thesubstrate “W” rests on pins (not shown) embedded in the surface of theHMDS bake plate block 73B so that only a small gap is maintained betweenthe substrate and the HMDS bake plate block 73B to reduce particlegeneration. In one embodiment, the heat exchanging device 73A is athermoelectric device that is used to heat the HMDS bake plate block73B. In another embodiment, as shown in FIG. 10C, the heat exchangingdevice 73A consists of a plurality of channels 73C formed in a surfaceof the HMDS bake plate block 73B, which are temperature controlled byuse of a heat exchanging fluid that continually flows through thechannels 73C. A fluid temperature controller (not shown) is adapted tocontrol the heat exchanging fluid and thus the HMDS bake plate block 73Btemperature. The heat exchanging fluid may be, for example, aperfluoropolyether (e.g., Galden®) that is temperature controlled to atemperature between about 30° C. and about 250° C. The heat exchangingfluid may also be a temperature controlled gas, such as, argon ornitrogen.

The lid assembly 75 generally contains a lid 72A, one or more o-ringseals 72C and an actuator assembly 72. The actuator assembly 72generally contains an actuator 72B and an o-ring seal 72D. The o-ringseal 72D is designed to isolate the HMDS processing region 77 from theenvironment outside of the HMDS process chamber 70. The actuator 72B isgenerally adapted to raise and lower the lid 72A so that a substrate canbe transferred to and from the lift pins 97D in the lift assembly 97.The lid 72A is adapted to form a seal between the HMDS base 74 using theo-ring seal 72D retained in the lid 72A (or on the HMDS base 74) to formthe processing region 76 and prevent the process gases used during theHMDS processing step 511 from escaping into the HMDS processing region77.

During processing the actuator 72B lowers the lid 72A to form a sealbetween the lid 72A, the o-ring seals 72C and the HMDS base 74 to form aleak tight seal. The process gas delivery system 71 delivers the processgas(es) to the processing region 76 to perform the HMDS processing step511. To deliver the process gas(es) an HMDS vaporization system 71Adelivers the HMDS vapor and a carrier gas to the processing regionthrough an isolation valve 71B and through the inlet 71F formed in theHMDS base 74, across the surface of the substrate, and out the outlet71G formed in the HMDS base 74, to a scrubber 71E. In one embodiment, apurge gas is delivered to the processing region 76 from a purge gassource 71C after the HMDS vapor containing processing gas has beendelivered to the processing region to remove any leftover HMDS vapor.The purge gas source 71C may be isolated from the HMDS vaporizationsystem 71A by use of an isolation valve 71D. In one embodiment, thepurge gas delivered from the purge gas source 71C is heated or cooled byuse of a conventional gas heat exchanging means (not shown) to controlthe temperature of the injected purge gas.

Post Exposure Bake Chamber

During an exposure process using a positive photoresist an insolublephotoresist material is transformed into a soluble material. During theexposure process, components in the photoresist that contain photoacidgenerators (or PAGs) generate an organic acid that can attack theunexposed areas of the photoresist and affect the sharpness of thepattern formed in the photoresist layer during the exposure process. Theattack of the unexposed photoresist is thus affected by the migration ofthe generated photoacid, which is a diffusion dominated process. Sincethe photoacid attack of the formed pattern is a diffusion dominatedprocess, the rate of attack is dependent on two related variables, timeand temperature. The control of these variables are thus important inassuring that the critical dimension (CD) uniformity is acceptable andconsistent from substrate to substrate.

In one embodiment, the PEB step 540 is performed in a bake chamber 90 asshown in FIG. 10B. In another embodiment, the PEB step 540 is performedin a HMDS process chamber 70 where a temperature controlled gas isdelivered from the purge gas source 71C to the processing region 76, toheat or cool the substrate retained on the HMDS bake plate assembly 73.

In another embodiment, the PEB step 540 is performed in a PEB chamber130. FIG. 10D illustrates a side view of the PEB chamber 130 in whichthe processing region 138 and mass of the PEB plate assembly 133 areoptimized to improve thermal uniformity, allow rapid changes intemperature, and/or improve process repeatability. In one embodiment,the PEB plate assembly utilizes a low thermal mass PEB plate assembly133 and a heat exchanging source 143 to rapidly heat up and/or cool downa substrate that is in communication with the top surface 133F of thePEB plate assembly 133. In this configuration the PEB plate assembly 133will generally contain a substrate supporting region 133B that has a topsurface 133F on which the substrate may rest, a heat exchanging region133A, and a base region 133C. The temperature of the substratesupporting region 133B is controlled by use of a temperature sensingdevice (not shown) that is used in conjunction with the systemcontroller 101 to vary the amount of energy delivered to the PEB plateassembly 133 by the heat exchanging region 133A.

The heat exchanging region 133A is a region enclosed between thesubstrate supporting region 133B, the base region 133C, and the sidewalls 133G. The heat exchanging region 133A is in communication with theheat exchanging source 143 through one or more inlet ports 133D and oneor more outlet ports 133E. The heat exchanging region 133A is adapted toaccept various heat exchanging fluids delivered from the heat exchangingsource 143 in order to heat or cool the substrate that is in thermalcommunication with the top surface 133F. In one aspect of the invention,the material thickness of the top surface 133F (i.e., distance betweenthe heat exchanging region 133A and the top surface 133F), and thus themass of the top surface 133F, is minimized to allow for rapid heatingand cooling of the substrate.

In one embodiment, the heat exchanging region 133A may contain aresistive heater or thermoelectric device to control the temperature ofthe substrate. In another embodiment the heat exchanging region 133A isadapted to control the temperature of the PEB plate assembly 133 by useof a radiation heat transfer method, for example, halogen lamps mountedbelow the substrate supporting region 133B.

The PEB plate assembly 133 may be formed by conventional means (e.g.,machining, welding, brazing, etc.) from one single material or it may beformed from a composite structure (e.g., structure containing manydifferent types of materials) that makes the best use of each material'sthermal conductivity, thermal expansion, and thermal shock properties toform an optimal PEB plate assembly 133. In one embodiment, the PEB plateassembly 133 is made from a thermally conductive material such asaluminum, copper, graphite, aluminum-nitride, boron nitride, and/orother material.

The heat exchanging source 143 generally contains at least one heatexchanging fluid delivery system which is adapted to deliver a heatexchanging fluid to the heat exchanging region 133A. In one embodiment,as shown in FIG. 10D, the heat exchanging source 143 contains two heatexchanging fluid delivery systems, which are a heat source 131 and acooling source 142.

In one embodiment, the heat source 131 is a conventional heat pipe whichis used to heat the substrate. In general a heat pipe is an evacuatedvessel, typically circular in cross sections, that may be back-filledwith a small quantity of a working fluid that transfers heat from theheat source 131 to a heat sink (e.g., the substrate supporting region133B and thus the substrate). The transfer of heat is performed by theevaporation of the working fluid in the heat source 131 and condensationof a working fluid in the heat exchanging region 133A. In operation theheat exchanging region 133A is evacuated by a vacuum pump (not shown)and then energy is added to a working fluid, retained in the heat source131, which creates a pressure gradient between the heat source 131 andthe heat exchanging region 133A. This pressure gradient forces the vaporto flow to the cooler section where it condenses, thus giving up energydue to the latent heat of vaporization. The working fluid is thenreturned to the heat source 131 by gravity, or capillary action, throughthe outlet port 133E and the outlet line 131B. The temperature of thesubstrate supporting region 133B is controlled by use of a temperaturesensing device (not shown) that is used in conjunction with the systemcontroller 101 by varying the amount energy (e.g., flow of the workingfluid) delivered to the heat exchanging region 133A.

In another embodiment, the heat source 131 delivers a heated gas, vaporor liquid from a fluid source (not shown) to the heat exchanging region133A to transfer heat to the substrate by a convective heat transfertype process. In this configuration the heated gas, vapor or liquid isdelivered to the heat exchanging region 133A through an inlet port 133Dfrom an inlet line 131A and exits the heat exchanging region 133Athrough the outlet port 133E where it is delivered to a waste collectionsource 142A. The waste collection source 142A may be a scrubber ortypical exhaust system.

In one embodiment, as shown in FIG. 10D, the heat exchanging source 143also contains a cooling source 142 which is adapted to cool thesubstrate to a desired temperature. In one embodiment of the coolingsource 142, the cooling source delivers liquid nitrogen to the heatexchanging region 133A to remove heat from the substrate supportingregion 133B and thus the substrate. In another embodiment, the coolingsource delivers a chilled gas, liquid or vapor to the heat exchangingregion 133A to cool the substrate. In one aspect of the invention thecooling source is used to cool the substrate to a temperature nearambient temperature.

In another embodiment of the PEB plate assembly 133, a heat exchangingdevice 134 is placed on the base region 133C to heat or cool the PEBplate assembly 133. In one aspect of the invention, the heat exchangingdevice 134 is used to cool the base region 133C, which is in thermalcontact with the substrate supporting region 133B through a plurality ofthermally conductive pillars 133H (only two shown). In thisconfiguration the substrate can be heated by the injection of a hotfluid from the heat source 131 and cooled by use of the heat exchangingdevice 134. This configuration may avoid the need for the cooling source142 to cool the substrate. The plurality of thermally conductive pillars133H are regions in which heat can be transferred from the substratesupporting region 133B to the base region 133C or vise versa. Theconductive pillars 133H may be arranged in any pattern, size or density(e.g., number of pillars 133H per unit area) that allows heat touniformly flow to or from the heat exchanging device 134 and allows thefluid delivered from the heat source to uniformly communicate with thesubstrate supporting region 133B.

Referring to FIG. 10D, in one aspect of the invention a lid assembly 137is placed over the substrate “W” and contacts the top surface 133F ofthe PEB plate assembly 133 to form a controlled environment around thesubstrate. The lid assembly generally contains the lid 137A and a lidactuator 139. The lid actuator 139 is a device that may be adapted toraise and lower the lid 137A so that the lift assembly 140 can transferthe substrate to and from the cluster tool robot (not shown) and the topsurface 133F. In one embodiment, the lid actuator 139 is an aircylinder. When the lid is in the processing position, as shown in FIG.10D, the lid contacts the top surface 133F and thus forms a processingregion 138 that surrounds the substrate to create a controlled thermalenvironment.

In one embodiment, the lid assembly 137 may contain a heat exchangingdevice 137B to control the temperature of the lid 137A and thus form anisothermal environment around the substrate to improve thermaluniformity across the substrate during processing. In this configurationthe heat exchanging device 137B adapted to act as a heat pipe in asimilar fashion as described above, to rapidly heat and cool the lidassembly 137. In one embodiment, the heat exchanging device 137B and theheat exchanging region 133A are both adapted to act as a heat pipe torapidly and uniformly control the temperature of the substrate. Inanother embodiment, the heat exchanging device 137B is adapted tocontrol the temperature of the lid assembly 137 by use of a radiative(e.g., heat lamps), or convective heat transfer means (described above).

In another embodiment of the lid assembly 137, a heated fluid source 141is connected to the processing region 138 through a lid inlet port 137Cto deliver a temperature controlled process fluid across the substratesurface and then out the lid outlet port 137D to a waste collectiondevice 141B. The heated fluid source 141 generally contain a fluidsource 141A, a fluid heater 141C and a waste collection device 141B(e.g., typically an exhaust system or scrubber). The fluid source 141Amay deliver a gas or liquid during processing to control the temperatureof the substrate. In one aspect of the invention the fluid source 141Amay deliver an inert gas, for example, argon, nitrogen, or helium.

Referring to FIG. 10D, the PEB chamber 130 generally contains anenclosure 136, the PEB plate assembly 133, and a lift assembly 140. Theenclosure 136 generally contains a plurality of walls (items 136B-D anditem 135) which tend to isolate the processes performed in the PEBchamber 130 from the surrounding environment. In one aspect of theinvention the enclosure is adapted to thermally isolate and minimizecontamination of the PEB chamber 130 from the surrounding environment.The lift assembly 147 generally contains a lift bracket 140A, anactuator 140B, a lift pin plate 140C, and three or more lift pins 140D(only two are shown in FIG. 10D), which are adapted to raise and lowerthe substrate “W” off an extended robot blade (not shown) and place thesubstrate on the surface of the PEB plate assembly 133 once the robotblade has been retracted. The lift pin holes 132 are configured to allowthe lift pins 140D to access the substrate so that it can be raised andlowered from the surface of the PEB plate assembly 133. The actuator140B may be an air cylinder or other conventionally available means ofraising and lowering the substrate. The robot blade (not shown) isadapted to enter the enclosure 136 through an opening 136E in the sidewall 136D of the enclosure.

Variable Heat Transfer Valve

FIG. 11A is side view that illustrates one embodiment of a plateassembly that may be used to rapidly heat and cool a substrate. The term“plate assembly” used hereafter is intended to generally describe anembodiment of the PEB plate assembly 133, the chill plate assembly 83,the bake plate assembly 93, or the HMDS bake plate assembly 73 which maybe adapted to benefit from this configuration. Referring to FIG. 11A, inone embodiment, a plate assembly 250 contains a conductive block 254which has a block surface 254A that is in thermal communication with asubstrate “W” during processing, a cooling region 253, a gap 259 formedbetween the conductive block 254 and the cooling region 253, an inletregion 257, an outlet region 258, and a fluid delivery system 275.

The conductive block 254 is used to support the substrate, and itcontains a heating device 255 which is adapted to heat a substrate thatis in thermal communication with the block surface 254A. The conductiveblock 254 may be made from a thermally conductive material such asaluminum, copper, graphite, aluminum-nitride, boron nitride, and/orother material. The heating device 255 may be a resistive heater or athermoelectric device that is used to heat the conductive block 254. Inanother embodiment, the heating device 255 consists of a plurality ofchannels formed in a surface of the conductive block 254 (not shown),which are temperature controlled by use of a heat exchanging fluid thatcontinually flows through the channels. A fluid temperature controller(not shown) is adapted to control the heat exchanging fluid and thus theconductive block 254 temperature. The heat exchanging fluid may be, forexample, a perfluoropolyether (e.g., Galden®) that is temperaturecontrolled to a temperature between about 30° C. and about 250° C. Theheat exchanging fluid may also be a temperature controlled gas, such as,argon or nitrogen.

The cooling region 253 is an area of the plate assembly 250 that isisolated from the conductive block 254 by the gap 259 and is maintainedat a low temperature to cool the conductive block 254 when a conductiveworking fluid is delivered to the gap 259 by the fluid delivery system275. The cooling region 253 contains a cooling device 265 that is usedto cool this area of the plate assembly 250. The cooling region 253 maybe made from a thermally conductive material such as aluminum, copper,graphite, aluminum-nitride, boron nitride, and/or other material. Thecooling device 265 may be a thermoelectric device that is used to coolthe cooling region 253. In another embodiment, the cooling device 265consists of a plurality of channels (not shown) formed in a surface ofthe cooling region 253, which are temperature controlled by use of aheat exchanging fluid that continually flows through the channels. Afluid temperature controller (not shown) is adapted to control the heatexchanging fluid and thus the cooling region 253 temperature. The heatexchanging fluid may be, for example, a perfluoropolyether (e.g.,Galden®) that is temperature controlled to a temperature between about5° C. and about 20° C. The heat exchanging fluid may also be atemperature controlled gas, such as, argon or nitrogen.

The fluid delivery system 275 generally contains a fluid delivery source270 that is adapted to deliver a conductive working fluid to the gap 259formed between the conductive block 254 and the cooling region 253. Thefluid delivery system 275 thus causes the conductive working fluid toflow from the fluid delivery system 275 through the inlet region 257into the gap 259 and then out the outlet region 258, where it isreturned to the fluid delivery system 275. The conductive working fluidis thus used to increase the thermal coupling between the cooling region253 and the conductive block 254 during different phases of the process,to heat and cool the substrate. The conductive working fluid may aliquid, vapor or gas that is able to increase the thermal couplingbetween the conductive block 254 and the cooling region 253. In oneembodiment, the conductive working fluid is liquid such as: a liquidmetal alloy of gallium, indium, and tin (e.g., galinstan); mercury (Hg);Galden; or polyethylene glycol. In another embodiment, the conductiveworking fluid is a gas, such as, helium, argon, or carbon dioxide (CO₂).

In one embodiment, the plate assembly 250 is used to bake the substratesin, for example, the PEB chamber to perform the PEB step 540. In thisconfiguration the substrate is first delivered to the block surface 254Awhile the conductive working fluid is flowing through the gap 259 andthus the cooling region 253 is in communication with the conductiveblock 254 and the block surface remains at a low temperature. Once thesubstrate contacts the block surface 254A the flow of the conductiveworking fluid is stopped and is removed from the gap 259 to decouple thecooling region 253 from the conductive block 254. In one embodiment, agas source 272 is used to force the remaining conductive working fluidback to the fluid delivery system 275. The conductive block 254 is thenheated by energy delivered from the heating device 255 until a desiredprocessing temperature is achieved in the conductive block 254. Aftermaintaining the desired processing temperature for a period of time theheating device 255 is shut off and the conductive working fluid isdelivered to the gap 259 to cool the conductive block 254 by increasingthe thermal coupling between the conductive block 254 and cooling region253. Once the substrate has reached a desired temperature it is removedfrom the processing chamber.

In one embodiment of the plate assembly 250, as shown in FIG. 11A, theblock surface 256 is purposely roughened by use of a mechanicalfabrication process, such as, bead blasting, knurling, or othermachining process to reduce the chance of thermal shock damage to theconductive block 254 material, and increase the surface area to couplethe cooling region 253 to the conductive block 254.

PEB Process Endpoint Detection System

In an effort to reduce the processing time in the bake chamber, PEBchamber and/or the HMDS process chamber and improve the repeatability ofthe process results, an endpoint detector can be integrated into thechamber to notify the system controller 101 that the process is completeor nearly complete so that it can then be transferred to the next chillchamber 80. This design thus minimizes the need to run the processlonger than necessary, or “over bake”, while still assuring that thechamber process is complete. This process is especially important in thePEB chamber due to the prevention of the generated organic acid duringexposure from attacking the unexposed areas of the photoresist.

To resolve this problem, in one embodiment, the process endpoint isdetermined by measuring the concentration of a previously identifiedPEB, HMDS, or bake chamber reaction byproducts contained in the gas, orvapor, above the surface of the previously deposited or exposedphotoresist layer. FIG. 12A illustrates one embodiment of an endpointdetection system 190 that is adapted to detect a change theconcentration of the byproducts diffusing from the surface of thephotoresist layer (not shown) on the surface of the substrate “W”. Inthis configuration a laser 191 emits a beam (see item “A”) at awavelength that is tuned so that the intensity of the signal received bythe detector 192 is decreased due to the interaction with the byproductsthat diffuse into the gas, or vapor, above the surface of thephotoresist during the processing step. The wavelength and intensity ofthe laser is also tuned so that the laser will not potentially causefurther exposure of the photoresist. In general the typical photoresistprocess byproducts will be, for example, hydrocarbon containingmaterials and carbon dioxide (CO₂). From the variation in intensitycaused by the change in the concentration of CO₂ or other organicbreakdown products evolving from the photoresist, an endpoint can beinferred. The wavelength, or wavelengths, emitted by the laser may bebetween about 500 nm and about 4000 nm. In one embodiment, where carbondioxide concentration is being detected, the wavelength of the laser isabout 1960 nm, which conventional laser diodes can readily achieve. Inanother embodiment, the wavelength of the beam emitted by the laser is4230 nm.

FIG. 12A is a side view of a bake chamber, PEB chamber or HMDS processchamber (see element 199) that contains a laser 191 that emits a beamthat crosses just above the surface of the photoresist contained on thesurface of the substrate. In this configuration the laser 191 anddetector 192 are mounted so that the emitted beam is parallel and inclose proximity to the photoresist layer on the surface of the substrate“W” which is retained on the plate assembly 193. The plate assembly 193may be, for example, the PEB plate assembly 133 or bake plate assembly93, which is used to process the substrate during the bake, PEB or HMDSprocess steps described above. Since the concentration of the evolvedbyproducts are the highest just above the surface of the photoresist theendpoint detection system 190 will generally have the highestsensitivity to changes in the concentration of the byproducts in thegas, or vapor in this configuration. An advantage of this configurationis that by projecting the beam over the surface of the photoresist, thedetected variation in intensity is the sum of the amount of byproductspassing through the beam over the whole length of the beam. This methodprovides a lower signal to noise ratio, and also corrects for variationsin the process during different phases of the process.

In another embodiment of the endpoint detector, a laser is used todetermine the photoresist layer thickness and/or sense a change in theindex of refraction of the photoresist layer to determine the endpointof the process. FIG. 12B illustrates one embodiment of a endpointdetection system 198 that can be used to measure the photoresist layerthickness and/or sense a change in the index of refraction of thephotoresist layer. The endpoint detection system 198 generally containsa laser 194, a beam splitter 195 and a detector 196. In one embodiment,shown in FIG. 12B, the endpoint detection system 198 also contains afiber optic cable 197 which can allow the laser 194, beam splitter 195and detector 196 to be positioned a desirable distance from theprocessing region 199A above the surface of the substrate.

In one embodiment of the endpoint detection process, the laser isdesigned to emit multiple wavelengths so that the photoresist thicknessand/or index of refraction changes can be monitored during theprocessing. The thickness of the photoresist is measured by detecting achange in multi-wavelength interference patterns that will change as thephotoresist thickness and index of refraction change during the process.In one embodiment of the endpoint detection process, the laser 194 emitsradiation to a beam splitter 195, where a percentage of the radiationemitted from the laser 194 passes directly through the beam splitter 195to the fiber optic cable 197. The fiber optic cable 197 then directs theemitted energy towards the surface of the substrate. The emittedradiation is then reflected, scattered or absorbed at the surface of thephotoresist layer (item “P”) and/or the surface of the substrate. Apercentage of the reflected radiation then travels back to the fiberoptic cable 197 where it directs the radiation to the beam splitter 195.The beam splitter 195 then reflects a percentage of the reflectedradiation to the detector 196 where the incident radiation is detected.

To detect when the endpoint of a process has occurred, using either ofthe embodiments described above, the detected signal may be comparedwith the signal or data collected from previously processed substrates.In one embodiment, obtaining post process measurements before theendpoint can be confidently detected may be required. FIG. 12Cillustrates a method of optimizing the endpoint detection process byusing data collected from previously processed wafers. The methodrequires that endpoint signals from two or more substrates be recordedfor reference or be stored in the memory of the system controller 101(see item A). The two or more substrates are then fully processed to andinspected to determine how the endpoint signal compared with the idealprocess (see item B). The inspection data is then used to determine theideal process time and actual endpoint signal, which is then used bysubsequent substrates processed in the chamber to determine the actualend of the process (see item C).

Improved Heat Transfer Design with Minimum Contact

To increase the system throughput, by reducing the chill chamber, bakechamber, PEB chamber and/or the HMDS process chamber processing times,various methods have been employed to increase the thermal coupling ofthe substrate to the heat exchanging device. While increasing thecontact between the substrate surface and the surface of the plateassembly (e.g., PEB plate assembly 133, chill plate assembly 83, etc.)will increase the thermal coupling and reduce the time it takes asubstrate to reach the desired process temperature, increasing contactis often undesirable since it will increase the number of particlesgenerated on the backside of the substrate, which can affect theexposure process results and also device yield.

To reduce the particle generation on the backside of the substrate thecontact of the substrate to the surface of the plate assembly can beminimized by use of an array of protrusions that space the substrate offthe surface of the plate assembly. While protrusions reduce the numberof particles generated they may tend to reduce the thermal couplingbetween the substrate and the plate assembly. Therefore, it is oftendesirable to minimize the height of the protrusions from the surface ofthe plate assembly to improve the thermal coupling, while also assuringthat the substrate will not touch the surface of the plate assembly.Prior art applications have typically used sapphire spheres that arepressed or placed into machined holes in plate assembly surface to actas the protrusions. It is often difficult to mechanically achievesufficiently good height control between the spheres and the surface ofthe plate assembly, since it needs to be very flat for this technique toassure that the substrate will not contact the plate assembly surface.These problems arise since the machining operations required to form thesurface features that hold the spheres, or pins, are all referenced tosome reference datum and thus does not take into account the variationin the surface topology of the plate assembly. This issue becomesespecially important where the height of the protrusions from thesurface of the plate assembly is about 30 micrometers.

Referring to FIG. 13A, to resolve these competing issues, in oneembodiment, an array of accurately controlled small contact areaprotrusions 171 are formed on the surface of the plate assembly 170 andthe substrate is biased towards the plate assembly to increase thethermal coupling between the substrate and the plate assembly. Thesubstrate may be biased towards the plate assembly 170 by use of avacuum chucking device, an electrostatic chucking device or otherconventional method of forcing the substrate against plate assembly. Thearray of accurately controlled small contact area protrusions 171 can beformed by use of a CVD and/or PVD deposition process. By use of a CVDand/or PVD deposition process a thin layer of material, of a controlledsize, can be uniformly deposited on the surface of the plate assembly toa desired height. The material deposited on the surface of the plateassembly 170 to form the protrusions 171 may be silicon dioxide (SiO₂),silicon (Si), a metal (e.g., nickel, titanium, titanium nitride,molybdenum, tungsten, etc.), a ceramic material, a polymeric material(e.g., polyimide, Teflon, etc.) or other material that is hard enough towithstand the biasing force without appreciable deformation and is noteasily abraded by the interaction with the backside of the substrate(e.g., diamond, diamond-like carbon, or boron nitride). This approach isadvantageous since the height of the protrusion above the surface of theplate assembly surface can be controlled to height that may be about tentimes smaller (e.g., 1/10^(th)) than on a state of the artconfiguration. The decrease in protrusion height will increase the heattransfer rate, so the wafer can heat much faster, and thus reduces thetime that the wafer spends transiting to the final temperature, whichreduces the variation in the diffusion and chemical reaction. It alsoensures closer thermal coupling between the wafer and heater, whichreduces the thermal impact of other chamber non-uniformities. Anotheradvantage of this approach is that by using more protrusions 171, themagnitude of the substrate bow is reduced since the substrate bow isinversely proportional to the fourth power of the distance between theprotrusions when an external pressure is applied to the substrate. Witheach protrusion 171 nominally the same height from the surface of theplate assembly, and the substrate being uniformly held above the surfaceof the plate assembly, with minimal bowing between protrusions, thethermal transfer from the plate assembly to the substrate will beuniform. Therefore, this design brings the temperature of the substratequickly and uniformly to the target temperature, while minimizing thegeneration of backside particles that are inherent in normal vacuumchucks.

To form the protrusions 171, in one embodiment, a mask (not shown) isplaced over the surface of the plate assembly which allows CVD or PVDmaterial to be deposited on certain defined areas of the substrate byuse of features or holes formed in the mask. In this way the size iscontrolled by the features formed in the mask and the height of theprotrusion is can be controlled by assuring a certain amount of materialis deposited on the surface of the plate assembly using a known PVD orCVD process deposition rate. In one embodiment, the protrusions 171which are deposited by a PVD or CVD process are about 100 micrometersthick.

FIGS. 13C and 13D illustrate one embodiment of a masking process where aselective CVD deposition process is used to deposit protrusions of adesired height. In this configuration, for example, a silicon dioxide ordiamond seed crystal 182A layer is imbedded in the plate assemblysurface 170A of plate assembly 170 made from Teflon coated aluminum. Inthis configuration a conventional CVD process may be adapted toselectively deposit a layer 182B of silicon dioxide or diamond film onthe seed crystal 182A. In this embodiment, a seed crystal 182A isimbedded into the plate assembly surface 170A so that the top surface ofthe seed crystal is substantially flush with the plate assembly surface170A. In one aspect of the invention an insertion tool (not shown) isused to assure the seed crystal 182A can be repeatably installed and itis flush with the plate assembly surface 170A. The insertion tool shouldbe made from a material is relatively incompressible, flat, and has apolished face. The insertion tool should have a working surface (notshown), which contacts with the seed crystal during insertion into theplate assembly, that is at-least as hard as the material from which theseed crystal 182A is made.

FIG. 13A illustrates one embodiment of a heat/cool assembly 180 whichmay be used in the chill chamber 80, the bake chamber 90, the PEBchamber 130 and/or the HMDS process chamber 70. In one embodiment, theheat/cool assembly 180 contains a plate assembly 170, and a vacuumsource 175, which are mounted in a processing chamber 186. The plateassembly 170 generally contains a plate 170B, plate assembly surface170A, protrusions 171, and a vacuum source port assembly 172. In thisconfiguration the vacuum source 175 is used to create a negativepressure in the vacuum port plenum 172B, thus causing air to flow intothe a plurality of vacuum ports 172A formed in the surface of the plateassembly 170, which creates a reduced pressure behind the substratewhich causes the substrate to be biased towards to the surface of theprotrusions 171. The plate 170B may be made from a thermally conductivematerial such as aluminum, copper, graphite, aluminum-nitride, boronnitride, and/or other material, and is in communication with a heatexchanging device 183A. While FIG. 13A illustrates a heat exchangingdevice 183A which has a different shape than that shown in the chillchamber 80, the bake chamber 90, the PEB chamber 130 and/or the HMDSprocess chamber 70 drawings described above, this embodiment is intendedincorporate all of the features described above.

In one embodiment, the plate assembly 170 also contains a gas sourceport assembly 173 and a gas source 174 to purge the edge of thesubstrate during processing to prevent the evaporating solvent vaporsfrom being deposited on the plate assembly surface 170A or the backsideof the substrate due to the reduced pressure generated behind thesubstrate (e.g., a vacuum chuck configuration). In this configurationthe gas source 174 is used to create a positive pressure in the gas portplenum 173B, thus causing the gas to flow out of a plurality of gasports 173A formed in the surface of the plate assembly 170. In oneembodiment the gas source 174 is adapted to deliver an inert gas to theedge of the substrate, such as, argon, xenon, helium, nitrogen, and/orkrypton. The gas source 174 may also be adapted to deliver a fluid tothe edge of the substrate.

FIG. 13B illustrates a plan view of the surface of the plate assembly170 with no substrate on top of the protrusions 171, to illustrate onepossible configuration of protrusions 171 (33 shown), vacuum ports 172A(˜367 shown), and gas ports 173A (˜360 shown). In general, the pluralityof protrusions 171 are spaced across the surface of the plate assembly170 so that the contact area can be minimized and the gap between thesubstrate and the plate assembly surface 170A is substantially uniform.The plurality of vacuum ports 172A are spaced across and around thesurface of the plate assembly 170 so that the substrate can be uniformlybiased towards the plate assembly 170 and thus the gap between thesubstrate and the plate assembly surface 170A is substantially uniform.In one embodiment, as shown in FIG. 13B an inner array of vacuum ports172A (see item “A”) is mirrored with an outer array of gas ports 173A(see item “B”), where the diameter of the inner array “A” is smallerthan the substrate diameter and the diameter of the outer array “B” isequal to or larger than the substrate diameter. In one embodiment, asmall ridge of the CVD or PVD deposited material that is used to formthe protrusions 171 (not shown) is placed between the inner array ofvacuum ports 172A and the outer array of gas ports 173A to minimize theamount of gas required to purge the edge of the substrate. FIGS. 13A-Balso illustrate a configuration having a lift assembly 87 and lift pinhole 189 extending through the plate assembly surface 170A to lift thesubstrate off the plate assembly surface 170A.

In one embodiment, the gas delivered from the gas source 174 is heatedprior to exiting the gas ports 173A to prevent cooling of the edge ofthe substrate during processing. In another embodiment, the length ofthe gas port plenum 173B in the plate assembly 170 is designed to assurethat the gas resides in the gas port plenum long enough for the injectedgas to substantially achieve the plate temperature before it exits thegas ports 173A.

Support Chamber

The support chamber 65 (FIGS. 4C, 4F and 4H) may be used to housecontainers, pumps, valves, filters and other support components that areuseful for completing the process sequence in the cluster tool 10.

In one embodiment, the support chamber 65 contains various metrologytools, such as, a particle measurement tool, an OCD spectroscopicellipsometry device, spectroscopic reflectometry and variousscatterometry devices to detect defects in the processed substrates,perform statistical process control, and/or allow the system tocompensate for variations in the incoming substrate quality. In one casea non-contact visible and/or DUV reflectometry technique can be used toperform measurements of film thickness and uniformity of the films onthe substrate in the cluster tool. A reflectometry tool can be purchasedfrom Nanometrics Incorporated, Milpitas Calif.

An integrated OCD spectroscopic ellipsometry tool may be used to enablecomplete film characterization and closed-loop control within thelithographic process without having to move the wafer to a standalonemetrology tool, saving transport time and eliminating potential handlingcontamination and damage. The integration of the various process controlmetrology capability directly into the cluster tool will thus helpimprove CD control and CoO. An OCD spectroscopic ellipsometry tool canbe purchased from Nanometrics Incorporated, Milpitas Calif.

Wafer Sequencing/Parallel Processing

In an effort to be more competitive in the market place and thus reduceCoO, electronic device manufacturers often spend a large amount of timetrying to optimize the process sequence and chamber processing time toachieve the greatest substrate throughput possible given the clustertool architecture limitations and the chamber processing times. In tracklithography type cluster tools, since the chamber processing times tendto be rather short, (e.g., about a minute to complete the process) andthe number of processing steps required to complete a typical tracksystem process is large, a significant portion of the time it takes toprocess a substrate is taken up by the processes of transferring thesubstrates in a cluster tool between the various processing chambers. Inone embodiment of the cluster tool 10, the CoO is reduced by groupingsubstrates together and transferring and processing the substrates ingroups of two or more. This form of parallel processing thus increasesthe system throughput, and reduces the number of moves a robot has tomake to transfer a batch of substrates between the processing chambers,thus reducing wear on the robot and increasing system reliability.

In one aspect of the invention, the track architecture is designed sothat substrates leave the cassette 106 mounted in the pod assemblies105A-D one-by-one, and are then grouped together in groups containingtwo or more substrates after being processed in the first processingstation. For example, when using the process sequence shown in FIG. 3A,the substrates might be grouped after completing the BARC coat step 510.In this configuration, the robot that serves the cassettes 106 andplaces each substrate in the first process stations may use a singleblade robot, but the robot (e.g., central robot 107) that picks up thesubstrates from the first process stations and places them in subsequentprocess stations, will be a robot that contains as many substrateretaining devices (e.g., robot blades) as there are substrates to begrouped. For example, as shown in FIG. 16A, in the case where twosubstrates are to be grouped together, a dual bladed type central robot107 may be used. In another aspect of the invention, the substrates areungrouped before they are transferred into the stepper/scanner 5, thenare regrouped again after the performing the PEB step 540, and are thenungrouped again at the last process station prior to being picked up bythe front end robot 108.

In one aspect of the invention, the substrates may be grouped togetherat the pod assembly 105 and transferred through the cluster tool ingroups, by use of a multiple bladed type front end robot 108, centralrobot 107 and rear robot 109. FIGS. 16A-D illustrate one embodiment of amultiple bladed robot. In this case, after each blade of the front endrobot 108 is loaded with a substrates, all of the transfer processesthrough the cluster tool is completed in groups. One will note that itis likely that the substrates will have to be de-grouped, i.e,transferred one at a time, at the stepper/scanner 5.

In one embodiment, the substrates are grouped in pairs and thus thetransferring process would include the grouping steps of singlesubstrate transfer in to the first process chamber, then dual substratetransfer through the system, then single substrate transfer to and fromthe stepper/scanner 5, then dual substrate transfer through the system,and single substrate transfer from the last chamber to the cassette. Inone embodiment, the central robot 107, as shown below in FIGS. 16A-B,contains a dual blade assembly 705 that contains at least one robotblade 711A on the first blade assembly 715A and at least one robot blade711B on the second blade assembly 715B to transfer substrates in groupsof two. In this configuration, the first blade assembly 715A and thesecond blade assembly 715B are a fixed distance apart, which correspondsto the vertical spacing of the two chambers in which the substrates areto be grouped. For example, if the substrates are grouped in pairs afterthe BARC coat step 510 is performed in CD1 and CD2 of the front endprocessing rack 52 shown in FIG. 4A, the spacing of the transferpositions in the CD1 and CD2 chambers is configured to allowtransferring of the substrates to the C12 and C9 chill chambers or B5and B2 bake chambers in the first central processing rack 152.Therefore, after the post BARC chill step 514 has been completed thecentral robot 107 may transfer the pair of substrates to one of thepairs of coater/developer chambers 60 retained in the second centralprocessing racks 154, such as chambers CD1 and CD2, CD2 and CD3, or CD3and CD4.

In one embodiment of the dual blade assembly 705, the horizontal spacingof the first blade assembly 715A relative to the second blade assembly715B is a fixed distance apart, which corresponds to the horizontalspacing of the two chambers in which the substrates are to be grouped.In this configuration, the first blade assembly 715A and the secondblade assembly 715B are aligned in the horizontal plane so that the dualblade assembly 705 can access chambers spaced horizontally.

Referring to FIG. 16D, in another embodiment, the spacing of the firstblade assembly 715A and the second blade assembly 715B are made avariable distance apart by use of an actuator 722 mounted on the dualblade assembly 705. Generally, the actuator 722 is adapted to vary thespacing between the various number of grouped substrates to coincidewith the desired spacing of the chambers to which the grouped substrateswill be transferred. In one aspect, the actuator 722 is mounted on thesupport 720 and is adapted to position the second blade assembly 715Bthat is attached to the second surface 720B. In this configuration theactuator 722 can vary the spacing “A” between the second blade assembly715B relative to the first blade assembly 715A by positioning the secondsurface 720B in a direction “B”. In one embodiment, the actuator 722 isa direct drive linear brushless servomotor that may be purchased fromDanaher Motion of Wood Dale, Ill. or Aerotech, Inc. of Pittsburgh, Pa.

In one embodiment, a batch develop process could be performed on thesubstrates, in which case the substrates would be transferred in a groupand then ungrouped to perform the develop process, after which theywould be regrouped transferred as a group.

Sequencing without Buffer Stations

In one aspect of the invention, the substrate processing sequence andcluster tool are designed so that the substrate transferring stepsperformed during the processing sequence are completed to chambers thatwill perform the next processing step in the processing sequence. Theprior art cluster tool configurations commonly install interim stations,or buffer chambers, in the process sequence so that the robot thatdropped off a substrate can complete other transferring steps and/orallow other robots to pick up and transfer the waiting substrate toanother desired position in the system. The step of placing a substratein a chamber that will not perform the subsequent processing step wastestime, decreases the availability of the robot(s), wastes space in thecluster tool, and increases the wear on the robot(s). The addition ofthe buffering steps will also adversely affect device yield, due to theincrease in the number of substrate handoffs which will increase theamount of backside particle contamination. Also, substrate processingsequences that contain buffering steps will inherently have differentsubstrate wafer histories, unless the time spent in the buffer chamberis controlled for every substrate. Controlling the buffering time willincrease the system complexity, due to an added process variable, and itwill likely hurt the maximum achievable substrate throughput. In a casewhere the system throughput is robot limited, the maximum substratethroughput of the cluster tool is governed by the total number of robotmoves to complete the process sequence and the time it takes to make therobot move. The time it takes a robot to make a desired move is usuallylimited by robot hardware, distance between processing chambers,substrate cleanliness concerns, and system control limitations.Typically the robot move time will not vary much from one type of robotto another and is fairly consistent industry wide. Therefore, a clustertool that inherently has fewer robot moves to complete the processingsequence will have a higher system throughput than a cluster tool thatrequires more moves to complete the processing sequence, such as clustertools that contain multiple buffering steps.

The various embodiments of the cluster tool shown on FIGS. 2A-G and14A-B have particular advantage over prior art configurations sincefewer moves and fewer robots are required to transfer the substratethrough the system. One example, is the ability of the front end robot108 to access the cassette(s) 106 and then directly place the substratein a first processing chamber (e.g., coater chamber 60A) and then afterprocessing in the first processing chamber deliver the substrate to asubsequent processing chamber (e.g., bake chamber 90). Prior artconfigurations require the use of multiple interim stations between thecassettes, process chambers and/or stepper/scanners, and multiple robotsto complete the process sequence through the cluster tool. In some priorart configurations, for example, it is common for a first robot to placea substrate in a first position, where it is picked up by second robotand placed in a second position in a processing chamber. After beingprocessed in the processing chamber the substrate is then placed back inthe first position by the second robot where it is picked up by thefirst robot or third robot to be transferred to another position in thesystem. This transferring process, or transfer path, is wasteful sinceit requires a separate robot to complete the transfer between the firstposition and the second position and it requires two non-value addedmoves to transfer the substrate. Adding extra robots and/or increasingthe non-value added moves can be costly due to decreased substratethroughput and will make the cluster tool less reliable. The importanceof this aspect may be better understood by noting that the reliabilityof a serial sequence is proportional to the product of the reliabilityof each component in the sequence. Therefore, a single robot having 99%up-time is always better than two robots having 99% up-time, since thesystem up-time for two serial robots each having 99% up-time is only98.01%. Since track lithography chamber processing times tend to berather short, and the number of processing steps required to complete atypical process sequence is large, the system throughput can besignificantly affected by the reliability of the system, the number ofwafer handoffs and the non-value added moves of a robot.

One advantage of the cluster tool configuration described herein is theability of the two or more robots to access processing chambers (e.g.,chill chamber 80, bake chambers 90, etc.) in the different main modules(e.g., front end module 306, central module 310, etc.). For example, inthe embodiment shown in FIG. 2F the front end robot 108 can access theprocessing chambers in the first central processing rack 312 and thesecond central processing rack 314 while the central robot 107 canaccess processing chambers in the first processing rack 308 and thesecond processing rack 309. The ability of a robot to access chambers inother main modules, or “robot overlap,” can be an important aspect inpreventing system robot transfer bottlenecks, since it allows an underutilized robot to help out a robot that is limiting the systemthroughput. Therefore, the substrate throughput can be increased, asubstrate's wafer history can be made more repeatable, and the systemreliability can be improved through the act of balancing the load eachrobot takes during the substrate sequence. In one aspect, the systemcontroller 101 is adapted to adjust the substrate transfer path throughthe cluster based on an optimized throughput or to work aroundprocessing chambers that have become inoperable. The feature of thesystem controller 101 which allows it to optimize throughput is known asthe logical scheduler. The logical scheduler prioritizes tasks andsubstrate movements based on inputs from the user and various sensorsdistributed throughout the cluster tool. The logical scheduler may beadapted to review the list of future tasks requested of each of thevarious robots (e.g., front end robot 108, central robot 107, rear robot109, one or more shuttle robots 110, etc.), which are retained in thememory of the system controller, to help balance the load placed on eachof the various robots. Use of a cluster tool architecture and systemcontroller 101 to work together to maximize the utilization of thecluster tool to improve CoO makes the wafer history more repeatable andimproves the system reliability.

In one aspect, the system controller 101 is further programmed tomonitor and control the motion of the end-effector of all robots in thesystem (e.g., dual blade assembly 705 (FIGS. 16A-C), blade assembly 706(FIG. 16F-G), etc.) to avoid a collision between the robots and improvesystem throughput by allowing robots to be in motion at the same time.This so called “collision avoidance system,” may be implemented inmultiple ways, but in general the system controller 101 monitors theposition of each of the robots by use of various sensor positioned onthe robot or in the cluster tool during the transferring process toavoid a collision. In one aspect, the system controller is adapted toactively alter the motion and/or trajectory of each of the robots duringthe transferring process to avoid a collision and minimize the transferpath length. In one embodiment, a “zone avoidance” system is used toprevent collisions between multiple robots. In one aspect of the zoneavoidance system, the system controller, through use of its hardware andsoftware components, is able to continually monitor, update and defineregions around each robot that are “open” or safe to move within. Thedefined “open” or safe regions are thus areas in which a robot may moveinto, or through, without the possibility of colliding with anotherrobot. In another embodiment of the collision avoidance system, thesystem controller is adapted to monitor and control multiple sensors(e.g., encoders on the various robot axes, position sensors, etc.) andemitters distributed around the cluster tool mainframe and on therobot(s) to continually track the actual position of each robot withinthe cluster tool to assure that the motion of two or more robots willnot cause them to move into the same space and thus collide. In oneaspect, the sensors are optical sensors that are positioned in variousvertical and/or horizontal orientations in the cluster tool to monitorthe position of each of the robots. In another aspect, each robot andits components are monitored by use of a sensing system that is able totriangulate the position of each of the various robot components by useof emitters positioned on the various robot components relative tomultiple sensors positioned in the mainframe. In one aspect, the sensingsystem contains emitters and sensors that are RF transmitters andreceivers.

FIG. 14A illustrates schematically a substrate transfer path which isintended to illustrate one example of the substrate flow through thecluster tool 10 where the number of buffering steps is minimized orcompletely eliminated. A transfer path is generally a schematicrepresentation of the path a substrate will travel as it is moved fromone position to another so that various process recipe steps can beperformed on the substrate(s). FIG. 14A illustrates the transfer path ofa substrate following the processing sequence described in FIG. 3A. Inthis embodiment, the substrate is removed from a pod assembly 105 (item# 105A) by the front end robot 108 and is delivered to a coater chamber60A (e.g., CD1, CD2, etc. (FIG. 4A)) following the transfer path A1, sothat the BARC coat step 510 can be completed on the substrate. Once theBARC process has been completed, the substrate is then transferred to abake chamber 90 (e.g., B1, B3, etc. (FIG. 4B)) by the central robot 107following the transfer path A2, where the post BARC bake step 512 iscompleted on the substrate. After completing the post BARC bake step 512the substrate is then transferred to the post BARC chill step 514 (e.g.,C1, C2, etc. (FIG. 4B)) by a shuttle robot 110 following the transferpath A3. After performing the post BARC chill step 514 the substrate isthen transferred by the central robot 107, following the transfer pathA4, to the coater chamber 60A (e.g., CD1, CD2, etc. (FIG. 4C)) where thephotoresist coat step 520 is performed. After performing the photoresistcoat step 520 the substrate is then transferred by the central robot107, following the transfer path A5, to the bake chamber 90 (e.g., B2,B4, etc. (FIG. 4B)) where the post photoresist coat bake step 522 isperformed. After performing the post photoresist coat bake step 522 thesubstrate is then transferred by a shuttle robot 110, following thetransfer path A6, to the chill chamber 80 (e.g., C1, C2, etc. (FIG. 4B))where the post photoresist chill step 524 is performed. After performingthe post photoresist chill step 524 the substrate is then transferred bythe central robot 107, following the transfer path A7, to the OEBRchamber 62 (e.g., OEBR1, etc. (not shown in FIG. 14A, see FIG. 4D))where the OEBR step 536 is performed. The substrate is then transferredto the stepper/scanner 5 following the transfer path A8 using the rearrobot 109. After the exposure step 538 is complete, the rear robot 109transfers the substrate to the PEB chamber 130 (FIG. 4D) following thetransfer path A9. After performing the PEB step 540 the substrate isthen transferred by the shuttle robot 110, following the transfer pathA10, to the chill chamber 80 where the post PEB chill step 542 isperformed. After performing the post PEB chill step 542, the substrateis then transferred by the rear robot 109 (or central robot 107),following the transfer path A11, to the developer chamber 60B where thedevelop step 550 is performed. After performing the develop step 550 thesubstrate is then transferred by the central robot 107, following thetransfer path A12, to the chill chamber 80 where it will be picked up bythe front end robot 108 to be transferred to the pod assembly 105following the transfer path A13.

In one aspect of the cluster tool 10 illustrated in FIG. 14A, thesubstrates are grouped together and transferred in groups of two ormore, such that the grouped substrates may move as a group along thetransfer paths A1-A7 and A10-A12. As noted above this form of parallelprocessing will increases the system throughput, and reduces the numberof moves a robot has to make to transfer a batch of substrates betweenthe processing chambers, thus reducing wear on the robot and increasingsystem reliability.

In one aspect of the cluster 10, as illustrated in FIG. 14A, thetransfer paths A3, A6, and/or A10 are completed by the central robot107. In one embodiment, the transfer path A11 is completed by a shuttlerobot 110 that is adapted to transfer substrates between the chillchamber 80 and the developer chamber 60B.

FIG. 14B illustrates schematically one example of a substrate transferpath through the FIG. 2F configuration of cluster tool 10, where thenumber of buffering steps can be minimized or completely eliminated.FIG. 14B illustrates the transfer path of a substrate following theprocessing sequence described in FIG. 3A. In this embodiment, thesubstrate is removed from a pod assembly 105 (item #105C) by the frontend robot 108 and is delivered to a coater chamber 60A following thetransfer path A1, so that the BARC coat step 510 can be completed on thesubstrate. Once the BARC process has been completed, the substrate isthen transferred to a bake chamber 90 (e.g., B1, B2, B3, etc. (FIG. 4G))by the front end robot 108 following the transfer path A2, where thepost BARC bake step 512 is completed on the substrate. After completingthe post BARC bake step 512 the substrate is then transferred to thepost BARC chill step 514 (e.g., C1, C2, etc. (FIG. 4G)) by a shuttlerobot 110 following the transfer path A3. After performing the post BARCchill step 514 the substrate is then transferred by the front end robot108, or central robot 107, following the transfer path A4, to theprocess chamber 370 configured as a coater chamber 60A (e.g., CD1, CD2,CD3, etc. (FIG. 4J)) where the photoresist coat step 520 is performed.After performing the photoresist coat step 520 the substrate is thentransferred by the central robot 107, following the transfer path A5, tothe bake chamber 90 (e.g., B2, B4, etc. (FIG. 4I)) where the postphotoresist coat bake step 522 is performed. After performing the postphotoresist coat bake step 522 the substrate is then transferred by ashuttle robot 110, following the transfer path A6, to the chill chamber80 (e.g., C1, C2, etc. (FIG. 4I)) where the post photoresist chill step524 is performed. After performing the post photoresist chill step 524the substrate is then transferred by the central robot 107, followingthe transfer path A7, to the OEBR chamber 62 (e.g., OEBR1, etc. (FIG.4I)) where the OEBR step 536 is performed. The substrate is thentransferred to the stepper/scanner 5 following the transfer path A8using the central robot 107. After the exposure step 538 is complete,the central robot 107 transfers the substrate to the PEB chamber 130following the transfer path A9. After performing the PEB step 540 thesubstrate is then transferred by the shuttle robot 110, following thetransfer path A10, to the chill chamber 80 where the post PEB chill step542 is performed. After performing the post PEB chill step 542, thesubstrate is then transferred by the central robot 107, following thetransfer path Al1, to the process chamber 370 configured as a developerchamber 60B (e.g., CD1, CD2, CD3, etc. as (FIG. 4J)) where the developstep 550 is performed. After performing the develop step 550 thesubstrate is then transferred by the front end robot 108, following thetransfer path A12, to the pod assembly 105. In one aspect, transfer pathA12 may be completed by picking up the substrate from the developerchamber 60B using the central robot 107, transferring the substrate tothe front end robot 108, and then transferring the substrate to the podassembly 105.

In one aspect, the transfer path A12 may be broken up into two steps(not shown) where the substrates are transferred to a chill chamber 80in the first processing rack 308 by the central robot 107 and thentransferred to the cassette using the front end robot 108. In thisconfiguration the chill chamber 80 acts as a “safe” position where thesubstrate can reside without being exposed to thermal energy orprocessing fluids which may affect the wafer history and amountcontamination on the processed substrate. A “safe” position may coincidewith holding the substrate on raised lift pins 87D (shown in lowerposition of FIG. 10A) or retaining the substrate on the chill plateblock 83B (FIG. 10A).

In one aspect, transfer path A12 may be completed by picking up thesubstrate from the developer chamber 60B using the central robot 107 andthen transferring the substrate to the pod assembly 105. In thisconfiguration the central robot 107 may be further adapted to translatea distance along the length of the cluster tool 10 by use of a slideassembly (not shown) and a translation actuator (e.g., linear servomotor, etc. (not shown)) to give the robot the desired reach to accessthe cassettes.

In one aspect of the cluster 10, as illustrated in FIG. 14B, thetransfer paths A3, A6, and/or A10 are completed by the central robot 107or the front end robot 108. In another aspect of the cluster tool 10illustrated in FIG. 14B, the substrates are grouped together andtransferred in groups of two or more, such that, the grouped substratesmay move as a group along the transfer paths A1-A7 and A10-A12.

Cluster Robots Design A. Vertical Rail Robot Design

FIG. 15A is an isometric view of cluster tool 10 which illustrates oneembodiment of the central robot 107. This embodiment of the centralrobot 107 contains a frog-leg robot (hereafter FLR or FL robot) assembly602 that is adapted to transfer substrates to and from the variousprocess chambers contained in the front end processing rack 52, thefirst central processing rack 152, the second central processing rack154 and/or the rear processing rack 202. The second central processingrack 154 has been removed from the FIG. 15A to highlight and clarify thecomponents contained in this embodiment. Referring to FIGS. 15A-D, theFLR assembly 602 generally contains an upper frog-leg (FL) robotassembly 610, a lower frog-leg (FL) robot assembly 620, and a lift railassembly 626. The lift rail assembly 626 generally contains a front rail614 and a back rail 612. This configuration thus contains two robotassemblies, the upper FL robot assembly 610 and the lower FL robotassembly 620, which are adapted to move independently of each other inboth the vertical and horizontal planes. In this embodiment, theindependent upper FL robot assembly 610 or the independent lower FLrobot assembly 620 each are able to move in the vertical plane, (i.e.,along the lift rail assembly 626), and are able to transfer thesubstrates to any position in the horizontal plane by movement of the FLrobot 625 from commands from the system controller 101. While FIGS.15A-D illustrate a configuration that contains two robot assemblies, theupper FL robot assembly 610 and the lower FL robot assembly 620, otherembodiments of the cluster tool 10 may contain three or more robotassemblies. In another embodiment of the cluster tool 10, a single FLrobot assembly is utilized to transfer substrates through the clustertool.

FIG. 15B is plan view of the cluster tool 10 in which the lower FL robotassembly 620 of the FL robot assembly 602 is exchanging a substrate froma process chamber contained in the rear processing rack 202.

FIG. 15C is an isometric view of the central robot 107 which highlightsthe various components of the upper FL robot assembly 610 and the lowerFL robot assembly 620. Typically the lift rail assembly 626 is mountedto a central module frame (not shown) that is part of the central module150. While FIG. 15A-D illustrate a configuration in which the FL robot625 in the upper FL robot assembly 610 or the lower FL robot assembly620 are facing each other (i.e., the upper FL robot is facing down andthe lower FL robot is facing up), but other configurations may be used,such as where the upper FL robot assembly 610 or the lower FL robotassembly 620 are both facing up or down, without varying from the scopeof the invention.

FIG. 15D, which is a plan view of a lower FL robot assembly 620, isintended to show that various components that are commonly found ineither the upper FL robot assembly 610 or the lower FL robot assembly620. The upper FL robot assembly 610 or the lower FL robot assembly 620will generally contain a FL robot 625 and a support assembly 624. In oneembodiment, as shown in FIGS. 15A-D, the FL robot 625 has two substratecarriers (i.e., 611A and 611B) that are adapted to transfer substratesbetween the various processing stations, but this configuration is notintended to limit the scope of the present invention since the number ofsubstrate carriers or the use of the frog-leg configuration is notintended to limit to the various aspects of the invention describedherein. An example of an exemplary FL robot having two substratecarriers that may be adapted to benefit from the invention is describedin commonly assigned U.S. Pat. No. 5,447,409, entitled “Robot Assembly”filed on Apr. 11, 1994, which is hereby incorporated by reference in itsentirety. Examples of other FL robots designs that may be adapted tobenefit from the invention are described in commonly assigned U.S. Pat.No. 5,469,035, entitled “Two-axis magnetically coupled robot”, filed onAug. 30, 1994 and U.S. Pat. No. 6,379,095, entitled Robot For HandlingSemiconductor Substrates”, filed on Apr. 14, 2000, which are herebyincorporated by reference in their entireties.

In one embodiment, where the FL robot 625 has two substrate carriers611A-B, the FL robot 625 will generally contain a dual axis motor 615,primary arms 618A-B, secondary arms 619A-D, wrist assemblies 621A-B, andsubstrate carriers 611A-B. In general by movement of the various axes ofthe dual axis motor 615 the primary arms 618A-B can be rotated in anopposing direction to extend or retract the substrate carriers 611A-B orrotated in the same rotational direction to rotate the substratecarriers 611A-B to a desired position. The FL robot 625 is mounted onthe support 613 of the support assembly 624 which supports and retainsthe robot assembly 625.

Referring to FIGS. 15C-D, the support assembly 624 generally containsthe support 613, and the motor assembly 617A, which is in communicationwith the front rail 614, and the motor assembly 617B, which is incommunication with the back rail 612, which are both attached to thesupport 613. The motor assembly 617A and motor assembly 617B generallycontain an actuator 630 and a guiding mechanism 631. In one embodiment,the actuator 630 is a direct drive linear brushless servomotor, whichthrough communication with the base component 616A-B (e.g., secondarycoil or “rotor” section), mounted on the lift rail assembly 626components, is adapted to independently raise or lower the attached FLrobot assembly components (e.g., items 610 or 620). In one embodiment,it may advantageous from a cost and ease of control point of view toonly have a single actuator 630 mounted to one of the lift rails (i.e.,front rail 614 and a back rail 612) and the other rail only have theguiding mechanism 631. A direct drive linear brushless servomotor thatmay be purchased from Danaher Motion of Wood Dale, Ill. or Aerotech,Inc. of Pittsburgh, Pa. In other embodiments, the actuator 630 may bestepper motor or other type of actuator that can be used to raise andlower the various FL robot assembly 610 or 620 components.

The guiding mechanism 631 is adapted to support and precisely guide theFL robot assembly 610 or FL robot assembly 620 components as they areraised and lowered on the lift rails to assure that the position andaccuracy of the motion of the FL robot assembly 610 or FL robot assembly620 are well controlled to allow consistent movement and transfer ofsubstrates. In one embodiment (not shown), the guiding mechanism 631contains a linear guide which supports and retains the FL robot assembly610 or 620 components. A linear guide may be purchased from DanaherMotion of Wood Dale, Ill. In another embodiment, as shown in FIGS.15C-D, wheels 619 are attached in an orthogonal configuration to themotor assemblies 617A-B and roll on a t-shaped rail structure 618 toposition and accurately control of the motion of the FL robot assembly610 or FL robot assembly 620 components.

In one aspect of the invention the FL robot assembly 602 contains two ormore FL robot assemblies (e.g., items 610, 620) which are synchronizedto allow substrates to be grouped and transferred together. Thisconfiguration may be advantageous since it will improve substratethroughput in the cluster tool. In one aspect, the two or more FL robotassemblies are physically coupled together so that the motion of eachblade of the FL robot assemblies moves in unison and thus are grouped.In this case the robot assemblies 610 may be a fixed distance apart andmove in a synchronized motion. In another aspect, the FL robotassemblies (e.g., items 610, 620) are mechanically coupled together sothat they maintained at a fixed distance apart, but each of the FLrobots 625 are able to move independently of each other (e.g., moveindependently in the horizontal plane).

In another aspect, the system controller 101 is utilized to control andsynchronize the movement of each of the two or more FL robot assembliesso that substrates can be transferred in groups of two or more. Forexample, if the central robot 107 is a FL robot assembly 602 thatcontains two robots, the transfer path A2, described in FIG. 14A, couldbe completed by using the upper FL robot assembly 610 and the lowerrobot assembly 620 to substantially simultaneously pick up substratesfrom two coater chambers 60A (e.g., CD1 and CD2 (FIG. 4A)) and thensubstantially simultaneously drop off the substrates into desired bakechambers 90 (e.g., B1 and B5 (FIG. 4B)). This configuration may beadvantageous since it can allow grouped moves to improve throughput, butalso allow for each robot to move independently if needed to completesome other desired task.

B. Articulated Robot

FIG. 16A is an isometric view of one embodiment of the central robot 107containing an articulated robot assembly 702 (hereafter AR assembly702). The AR assembly 702 is adapted to transfer substrates to and fromthe various process chambers contained in the front end processing rack52, the first central processing rack 152, the second central processingrack 154 and/or the rear processing rack 202. The second centralprocessing rack 154 has been removed from FIG. 16A to highlight andclarify the components contained in this embodiment. The AR assembly 702generally contains articulated robot 710 and a dual blade assembly 705.The articulated robot 710 is generally a 6-axis articulated robot whichcan be purchased from Mitsubishi Electric Corporation, of Tokyo, Japan,Kawasaki Robotics (USA), Inc. of Wixom, Mich., and Staubli Corp. ofDuncan, S.C. In one embodiment, the 6-axis articulated robot is a modelnumber TX90 purchased from Staubli Corp. of Duncan, S.C. The articulatedrobot 710 has a robot base 713A and a mechanical interface 713B, whichconnect the robot to the cluster tool and the end-effector assembly(e.g., dual blade assembly 705, blade assembly 706, etc.) to the robot,respectively. In general, the 6-axis articulated robot is advantageoussince the reach of the articulated robot is far superior fromconventional robots due to its multiple axis and multiple linkagedesign, the reach of multiple articulated robots can more easily“overlap” since the motion of the end-effector, which retains andtransfers the substrate(s), is not linked to motion of the robot base713A which allows the robots to more effectively avoid each other whiletransferring substrates, and/or the reliability of the articulatedrobots exceeds most conventional robots.

The dual blade assembly 705 generally contains a support 720, and two ormore blade assemblies 715 (e.g., first blade assembly 715A, a secondblade assembly 715B, etc.). The support 720 attaches to and is guided bythe articulated robot 710 so that a blade in a first blade assembly 715Aand a blade in a second blade assembly 715B can each pick-up and/orplace a substrate in a two different processing chambers retained in aprocessing rack. The pitch (see item “A”), or the distance, between therobot blades is fixed by the distance between the first supportingsurface 720A and second supporting surface 720B, and is designed tocoincide with the pitch between two of the processing chambers retainedin the processing racks. Therefore, the distance between the transferposition of the bake chambers labeled B1 and B4, for example, in thefirst central processing rack 152, would coincide with the pitch betweenthe coater/developer chambers labeled CD1 and CD2 in the front endprocessing rack 52, so that after completing the BARC coat step 510 thesubstrates could then be transferred to bake chambers labeled B1 and B4to complete the post BARC bake step 512. Referring to FIG. 16B, thepitch “A” is generally defined as the distance, or spacing, between theblades 711A-B in a normal direction to the substrate receiving surfaces712A-B. In one embodiment, the pitch (see item “A”), is a distancebetween about 100 mm and about 1200 mm, and preferably between about 300mm and about 700 mm. While the dual blade assembly 705 is illustrated inconjunction with the articulated robot assembly 702, otherconfigurations may utilize the dual blade assembly 705 on other types ofrobots without varying from the basic scope of the invention.

In one aspect, the substrate receiving surfaces 712A-B are adapted toretain a substrate positioned on the blade (not shown) by use of an edgegripping mechanism that holds the substrate in position on the robotblade. The edge gripping mechanism can be adapted to grab the edge ofthe substrate at multiple points (e.g., 3 points) to hold and retain thesubstrate.

Referring to FIG. 16B, in one embodiment, each blade assembly 715 (e.g.,first blade assembly 715A or second blade assembly 715B), generallycontains one or more robot blade actuators 721 (see items 721A-721B) andone or more robot blades 711 (see items 711A-711B). The robot bladeactuators 721 may be a direct drive linear brushless servomotor or otherequivalent device that is able to control the motion and position of therobot blade 711. Generally, the pitch between the robot blades will notaffected by the actuation, or translation, of one robot blade relativeto another robot blade, since it is preferred that the actuated bladetranslate in a plane that is parallel to the other robot blade.

FIG. 16C illustrates one embodiment of the dual blade assembly 705 whichcontains one pair of blade assemblies 715A and 715C mounted on thesupport bracket 722A positioned on the first supporting surface 720A anda second pair of blade assemblies 715B and 715D mounted on the supportbracket 722B positioned on the second supporting surface 720B. FIG. 16Cfurther illustrates a configuration where robot blade 711B is shown inan actuated position while the other blades (e.g., 715A and 715C-D) areshown in their retracted position. In one aspect of the dual bladeassembly 705, each robot blade 711 (e.g., 711A-D), contained in itsrespective blade assembly 715 (e.g., 715A-D), may be independentlyactuated by use of the system controller (not shown) and its robot bladeactuator 721 (e.g., 721A-D). In one aspect, as shown in FIG. 16C, eachrobot blade 711 in each of the pairs may be physically positioned in anorientation that is substantially horizontally aligned over each otherand vertically spaced apart (often termed “over/under” configuration),so that a substrate can be retained on each blade at the same time. Theover/under blade configuration may be advantageous, for example, wherethe robot has to remove a substrate from a processing chamber prior toplacing the next substrate to be processed in the same processingchamber, without having to leave its basic position to move the“removed” substrate to another chamber. In another aspect, thisconfiguration may allow the robot to fill up all of the blades and thentransfer the substrates in groups to a desired location in the tool. Forexample, in FIG. 16C four substrates could be transferred on the fourblades. This configuration also has a further advantage that allowssubstrates transferred in groups to be ungrouped by dropping-off orpicking-up the substrates one at a time from each of the blades 711A-D.In other embodiments, three or more stacked blades mounted on each ofthe supporting surfaces (e.g., 720A and 720B FIG. 16B) may be used inplace of the “pairs” of robot blades to further facilitate the transferof multiple substrates in groups.

FIG. 16E illustrates a cross-sectional view of an over/under type dualblade assembly 705 where a single blade (item#715D) has been extended toaccess a substrate “W” in a pod assembly 105 so that it can be picked-upor dropped-off in the cassette 106. This configuration will allowgrouped transfer of the substrates through the system and then singledrop-off and/or pick-up of substrates in stations that can only acceptone substrate at a time (e.g., cassette 106, stepper/scanner 5, etc.).

In one aspect of the invention, to perform a single substrate transfertask using a robot that contains two or more fixed robot blades, i.e.,contains no robot blade actuators 721, the robot is adapted to“re-position,” e.g., flip, rotate, and/or detach, at least one of therobot blades so that the “re-positioned” blade(s) will not interferewith the process of transferring a substrate on another robot blade. Inthis configuration a special position or chamber (e.g., supportchambers) may be adapted to receive a robot blade and reposition it in adesired orientation to allow substrates to be transferred using otherrobot blades. The ability to re-position one or more of the robot bladesmay be especially useful when one or more processing chambers in agrouped transferring sequence is not operational, and thus will notallow a blade to enter the processing chamber, since it will allow otheradjacent processing chamber positions to be utilized.

FIGS. 16F and 16G are isometric views of one embodiment of the front endrobot 108 or the rear robot 109 containing a single blade typearticulated robot assembly 703. The single articulated robot assembly703 (hereafter SA robot assembly 703) is adapted to transfer substratesto and from the various process chambers contained in the front endprocessing rack 52 and the pod assembly 105, or the rear processing rack202 and stepper/scanner 5, depending on whether the robot is a front endrobot 108 or the rear robot 109. The SA robot assembly 703 generallycontains a articulated robot 710 and a blade assembly 706. Thearticulated robot 710 is generally a 6-axis articulated robot which canbe purchased from Mitsubishi Electric Corporation, of Tokyo, Japan,Kawasaki Robotics (USA), Inc., of Wixom, Mich., and Staubli Corp. ofDuncan, S.C.

Referring to FIG. 16G, the blade assembly 706 generally contains asupport 718 and a blade assembly 715 (e.g., first blade assembly 715A),described above. The support 718 attaches to and is guided by thearticulated robot 710 so that robot blade 711 in a blade assembly 715can pick-up and/or place a substrate in a processing chamber retained ina processing rack. In one embodiment, the single blade articulated robotassembly 703 may contain a pair of blade assemblies 715 (e.g., items715A and 715C) such as one of the pairs illustrated and described inconjunction with FIG. 16C.

In one embodiment, the front end robot 108 or the rear robot 109 are adual blade assembly 705 as illustrated and described above inconjunction with FIGS. 16A-D and 14A-B. This configuration will allowgrouped transfer of the substrates throughout the system and thusincrease throughput, CoO and system reliability.

FIG. 16H is an isometric view of one embodiment of a moveablearticulated robot (e.g., AR assembly 702 is shown) that is adapted toallow the articulated robot base 713 to be translated and positionedalong the length of a cluster tool by use of a slide assembly 714. Inthis configuration the articulated robot base 713 is connected to anactuator assembly 717 of the slide assembly 714, which is adapted tomove the AR assembly 702 to a desired position in the cluster tool byuse of commands from the system controller 101. The slide assembly 714generally contains an actuator assembly 717, a cover (not shown), and abase 716. The base 716 supports and mounts the AR assembly 702 and slideassembly components to the cluster tool. The cover, not shown forclarity, is used to enclose the actuator assembly 717 and other slideassembly features to prevent generated particles from making their wayto the processing chambers and prevent damage to these features duringmaintenance of the cluster tool. The actuator assembly 717 may generallycontain an actuator 719 and a guiding mechanism 723 (elements 723A and723B. In one embodiment, as shown in FIG. 16H, the actuator 719 is adirect drive linear brushless servomotor, which through communicationwith the base component 719A (e.g., secondary coil or “rotor” section)mounted on the base 716 and a slider 719B (e.g., stator), is adapted tomove the AR assembly 702 along the length of the slide assembly 714. Adirect drive linear brushless servomotor that may be purchased fromDanaher Motion of Wood Dale, Ill. or Aerotech, Inc. of Pittsburgh, Pa.In other embodiments, the actuator 719 may be stepper motor or othertype of actuator that can be used to position the robot. The guidingmechanism 723 is mounted to the base 716 and is used to support andguide the robot as it is moved along the length of the slide assembly714. The guide mechanism 723 may be a linear ball bearing slides or aconventional linear guide, which are well known in the art.

While FIG. 16H illustrates a single robot mounted to the slide assembly714, in other embodiments two or more robots may be affixed to the sameslide assembly. This configuration can reduce cost by reducing thenumber of redundant parts and improve the precise motion of each of therobots relative each other. Also, while FIG. 16H illustrates a dualblade articulated robot mounted to the slide assembly 714, the type ofrobot or number of blades is not intended to be limiting of the scope ofthe invention.

FIG. 16I illustrates a cross-sectional view of one embodiment of a robothaving two fixed blades that are positioned to pick-up two substratespositioned in the two separate vertically stacked pod assemblies 105. Inthis configuration the multiple bladed robot is adapted to pick-upand/or drop-off substrates positioned in the two cassettes (item #s106A-B) to allow grouped substrate transferring process to be performedat the start and/or the end of the substrate transferring sequence. Inone aspect, the cassettes and thus pod assemblies are spaced a distance“A” apart so that a robot can access the substrates in similar positionsin each cassette. In one aspect, when at least one cassette (e.g., item106A) is not required various regions (e.g., items 731A, 731B, etc.) mayformed above and/or below one of the other cassettes to allow a robotthat has a fixed blades to access a first cassette with a first fixedrobot blade without causing a collision with a second fixed robot bladeand a cluster tool wall 731C. Therefore, in one aspect a region 731B maybe formed to allow the first blade 711A to access a position in thelower cassette 106B while allowing the lower blade 711B to enter theregion 731B without colliding with the wall 731C. While FIG. 16Iillustrates a configuration where the robot blades 711A-B are fixed tothe support surfaces 720A-B of the support 720, and thus do not utilizea robot blade actuator 721, other embodiments having robot bladeactuators can be used without varying from the basic scope of theinvention.

C. Shuttle Robot.

FIGS. 17A-C illustrate various embodiments of a shuttle robot 110 thatcan be adapted to transfer substrates between adjacent chambers in thevarious processing racks. The design here may be advantageous for usewhen transferring substrates between a bake process chamber (e.g., bakechamber 90, HMDS process chamber 70, PEB chamber 130, etc.) and a chillchamber 80 which are used in subsequent processing steps, for example,between the post BARC bake step 512 and the post BARC chill step 514 andthe post photoresist coat bake step 522 and the post photoresist chillstep 524. The shuttle robot 110 is thus used to reduce the work load onthe various system robots, such as, the front end robot 108, the centralrobot 107, and the rear robot 109, thus allowing the system robots to doother tasks while the other processing steps are completed on thesubstrates.

FIG. 17A is an isometric view of one configuration in which the shuttlerobot 110 is used to transfer substrates between three adjacentprocessing chambers, such as between two bake chambers 90 and a chillchamber 80. This configuration may thus be used between, for example, abake chamber B1, chill chamber C1 and bake chamber B2 in the firstcentral processing rack 152 shown in FIG. 4B.

FIG. 17B is an isometric view of one configuration in which the shuttlerobot 110 is used to transfer substrates between two adjacent processingchambers, such as between a bake chamber 90 and a chill chamber 80. Thisconfiguration may thus be used between, for example, a bake chamber B1and chill chamber C7 contained in the front end processing rack 52 shownin FIG. 4A, a PEB bake chamber PEB1 and chill chamber C3 contained inthe rear processing rack 202 shown in FIG. 4D, or a HMDS process chamberP1 and chill chamber C1 contained in the front end processing rack 52shown in FIG. 4A.

FIG. 17C is an isometric view of the backside of the adjacent processingchambers shown in FIG. 17A or 17B which is intended to show anembodiment of the shuttle robot 110. The shuttle robot 110 generallycontains a robot blade 111 and a shuttle robot actuator assembly 120. Ashuttle robot actuator assembly 120 generally contains a robot bladeactuator 112, a slide assembly 113 and a robot drive assembly 119. Therobot blade 111 generally contains a substrate retaining area 111A and amounting region 111B. The mounting region 111B is an area of the robotblade 111 that is used to attach the robot blade 111 to the robot bladeactuator 112 (see mount 112A). The substrate retaining area 111A may beadapted to act as a conventional vacuum chuck, which is attached to avacuum generating source (not shown), to hold a substrate during thesubstrate transferring process. The robot blade actuator 112 is a devicethat is used to raise and lower the robot blade 111 so that thesubstrate can be transferred from one processing chamber to another. Inone embodiment, the robot blade actuator 112 is an air cylinder. In oneembodiment, a linear actuator (e.g., linear brushless servo motor (notshown)) is mounted between the robot blade actuator 112 and the robotblade 111, so that the robot blade 111 can be extended and/or retracted(e.g., into or out of the chamber) to complete the substrate transferprocess with the lift pins or other substrate retaining features in theprocessing chamber.

In one embodiment, the slide assembly 113 is a linear ball bearing slidethat guides the shuttle robot 110 as it transfers the substrates betweenthe various processing chambers. The slide assembly 113 generallycontains a shuttle 113A on which the robot blade actuator 112 isattached. The clamp 118 is used to attach the shuttle 113A to the belt117 of the robot drive assembly 119 to allow the robot drive assembly119 to move the robot blade 111 between the various processing chambers.

In one embodiment, as shown in FIG. 17C, the robot drive assembly 119 isa belt and pulley type system which is used move the robot along thelength of the slide assembly 113. In this configuration the robot driveassembly 119 will generally contain two or more idler pulleys 116A-B, abelt 117 and a motor 115 that is adapted to drive and control theposition of the robot. In one embodiment, the motor 115 is a DCservomotor with an integrated encoder so that the system controller 101can keep track of and control the position of the shuttle robot 110. Inanother embodiment of the robot drive assembly 119, the belt and pulleytype system is replaced with a direct drive linear brushless servomotorthat may be purchased from Danaher Motion of Wood Dale, Ill.

Integrated Bake/Chill Chamber

FIG. 18A illustrates one embodiment of an integrated bake/chill chamber800 that may be used in conjunction with the various embodiments of thecluster tool. In general the integrated bake/chill chamber 800 has threemajor processing regions: an input region 830, a chill region 810 and abake region 820, which are adapted to perform a process sequence wherevarious bake method steps (e.g., post BARC bake step 512, PEB step 540,etc.) and/or chilled method steps (e.g., post BARC chill step 514, postPEB chill step 542, etc.) are performed. The integrated bake/chillchamber 800 may contain two or more access ports 802 (two shown in FIG.18A) in the enclosure 804, which are adapted to allow an external robot(e.g., front end robot 108, the central robot 107, etc. (not shown)) toaccess the input region 830 and/or the chill region 810 to pick up ordrop off substrates. The enclosure 804 generally contains an inputstation enclosure 804A, a chill chamber enclosure 804B and a bakechamber enclosure 804C, that are adapted to isolate the various regionsof the integrated bake/chill chamber 800.

In one embodiment, the input region 830 is used to receive a substratefrom an external robot. The input region 830 is generally an enclosedregion that contains a substrate exchanging device, such as lift pins836 or some other similar device, that is adapted to allow an externalrobot to pick up or drop-off a substrate in the integrated bake/chillchamber 800. The input region 830 is also configured to allow a chilledtransfer arm assembly 832 to pick-up and drop off substrates from thelift pins 836.

The chilled transfer arm assembly 832 generally contains a chilled blade833 that has a blade receiving surface 834 and a plurality of cut-outs835 that are adapted to allow the chilled blade 833 to pick-up, retainand drop-off substrates from the various substrate exchanging devices inthe various processing regions of the integrated bake/chill chamber 800.In one embodiment, the chilled blade 833 of the chilled transfer armassembly 832 contains a heat exchanging device 837 (FIG. 18B) that is inthermal communication with the blade receiving surface 834 so that thetemperature of a substrate positioned on the blade receiving surface 834can be temperature controlled. In one aspect, the temperature of theheat exchanging device 837 is monitored and controlled by use of atemperature controlling device 838 (FIG. 18B) that is in communicationwith the system controller 101. The heat exchanging device 837 may be athermal electric device and/or embedded heating elements so that thetemperature of the substrate can be controlled. In one aspect, the heatexchanging device 837 may contain a plurality of fluid channels (notshown) that are embedded in the chilled blade 833, that are configuredto allow a temperature controlled heat exchanging fluid to flowtherethrough. The blade receiving surface 834 may contain mechanicalfeatures (not shown) to retain a substrate on the receiving surface. Inone aspect, the blade receiving surface 834 may contain a plurality ofvacuum ports (not shown) that are connected to a vacuum source (notshown) to retain the substrate and assure intimate contact between thesubstrate and the blade receiving surface 834.

FIG. 18B illustrates one embodiment of the chilled transfer arm assembly832 that utilizes a chilled blade actuator assembly 839, similar to theshuttle robot actuator assembly 120 described above in conjunction withFIG. 17C, which is used to control the position of the chilled bladeassembly 832 in any of the various processing regions of the integratedbake/chill chamber 800. One will note, for clarity reasons, the itemnumbers of the common components used in the chilled blade actuatorassembly 839 and shuttle robot actuator assembly 120 have not beenchanged. In one aspect of the chilled transfer arm assembly 832, thesystem controller 101 is utilized to position, both vertically andhorizontally, the chilled blade assembly 832 in any of the variousprocessing regions of the integrated bake/chill chamber 800. The chilledblade 833 is positioned by use of a chilled blade actuator assembly 839,on which is mounted one or more surfaces of the integrated bake/chillchamber 800. Referring to FIGS. 18A-B, the enclosure 804 contains aplurality of enclosure cut-outs 806, which allow the chilled blade 833to transfer a substrate between the various processing regions of theintegrated bake/chill chamber 800.

Referring to FIG. 18A, the chill region 810 contains the chill chamber80 components illustrated and described in reference to FIG. 10A. In oneaspect of the chill region 810, the enclosure 804B contains one or moreenclosure cut-outs 806 to allow the chilled transfer arm assembly 832 tofacilitate the transfer of a substrate between the various processingregions of the integrated bake/chill chamber 800.

The bake region 820 may contain all of the components of a bake chamber90, HMDS process chamber 70, or a PEB chamber 130 as illustrated anddescribed in reference to FIGS. 10B-D. In one aspect of the bake region820, the enclosure 804C contains one or more enclosure cut-outs 806 toallow the chilled transfer arm assembly 832 to transfer a substratebetween the various processing regions of the integrated bake/chillchamber 800.

When the integrated bake/chill chamber 800 is in use, an external robotdelivers the substrate to the lift pins 836 of the input region 830through an access port 802. The chilled blade 833, which is positionedbelow the lift pins 836, then moves vertically to remove the substratefrom the lift pins 836 and positions the substrate on the bladereceiving surface 834. The chilled blade 833 is then moved to the bakeregion 820 where the chilled blade 833 deposits the substrate and thenexits the bake region 820 so that a bake process can be performed on thesubstrate. After the bake process has been performed the chilled blade834 picks up the substrate from the bake region 820, transfers thesubstrate to a substrate exchanging device in the chill region 810, andthen exits the chill region 810. After a chill process has beenperformed, the substrate is removed from the chill region 810 throughthe access port 802 by use of the external robot. In one aspect, afterthe chill process has been performed the chilled blade 833 removes thesubstrate from the chill region 810 and deposits the substrate on thelift pins 836 in the input region. This configuration may beadvantageous since the chill region 810 is made available to complete achill process on a new substrate and/or it allows the external robot topickup the substrate from the same position that it deposited thesubstrate.

Integrated Scanner/Stepper with PEB Cluster Tool Configuration

FIG. 19A illustrates a plan view of one embodiment of the invention inwhich a cluster tool contains a cluster tool 10A and a stepper/scanner5A. In this configuration a PEB chamber 5C (i.e., element 130 describedabove (FIG. 10D)) is integrated into a stepper/scanner 5A and thestepper scanner is detached from the cluster tool 10A. Thisconfiguration has an advantage over the prior art since the throughputof the stepper/scanner is often many times greater than the throughputof the track system type cluster tool, and thus dedicating onestepper/scanner to a single track system wastes the stepper/scanner'sexcess throughput capacity. This embodiment allows a singlestepper/scanner to service multiple track systems while also stabilizingthe photoresist after performing the exposure process by performing thePEB step 540 and the post PEB chill step 542 in the stepper/scanner.

In one embodiment, as shown in FIG. 19A, the cluster tool 10A maycontain the front end module 50, a central module 150, and a rear module200 as illustrated and described above in relation to FIG. 1B. In thisconfiguration, the cluster tool 10A is not integrated with thestepper/scanner and thus the rear robot 109 (shown in FIG. 2E) has beenremoved from the rear module 200 to save cost and reduce systemcomplexity. In other embodiments, the cluster tool 10A may contain adifferent number of processing chambers and/or processing racks withoutdeviating from the basic scope of the invention.

In this configuration the stepper/scanner 5A will generally contain oneor more PEB chambers 5C and one or more chill chambers 5B (i.e., item 80described above (FIG. 10A)). The number of PEB chambers and chillchambers that are required is dependent on the throughput need of thestepper/scanner 5A and the processing time in the PEB and chillchambers. In practice the PEB chambers 5C and/or chill chamber 5B mayact as an input stage and/or an output stage of the stepper/scanners, sothe stepper/scanner robot (not shown) has a place to pickup and returnsubstrates. In one embodiment, where the PEB chamber 5C is adapted toboth heat and cool the substrate (described above), at least two PEBchambers may be integrated into the stepper/scanner in the positions 5Band 5C, not shown in FIG. 19A. In one embodiment, where the PEB chamber5C is adapted to both heat and cool the substrate (described above),only one PEB chamber is integrated into the stepper/scanner 5.

FIG. 19B illustrates one embodiment of method steps 504 containingvarious process recipe steps that may be used in conjunction with thecluster tool 10A and stepper/scanner 5A illustrated in FIG. 19A. In thisembodiment, the processing sequence can be split into three distinctparts, the cluster tool phase 1, the stepper/scanner phase, and thecluster tool phase 2. The cluster tool phase 1 includes all of theprocessing steps completed before being transferred to thestepper/scanner tool which may include: a remove substrate from pod 508Astep, a BARC coat step 510, a post BARC bake step 512, a post BARC chillstep 514, a photoresist coat step 520, a post photoresist coat bake step522, a post photoresist chill step 524, an optical edge bead removal(OEBR) step 536, and a place in pod step 508B. The pod of substrates isthen removed from the cluster tool 10A and placed on the stepper/scanner5A so that the stepper scanner can perform its processing steps whichmay include: a remove substrate from pod 508A step, an exposure step538, a post exposure bake (PEB) step 540, a post PEB chill step 542, anda place in pod step 508B. The pod of substrates are then removed fromthe stepper/scanner 5A so that the cluster tool phase 2 steps can becompleted which may include: a place in pod 508A step, a develop step550, a post develop chill step 554 and a place in pod step 508B. Inother embodiments, the sequence of the method steps 504 may berearranged, altered, one or more steps may be removed, or two or moresteps may be combined into a single step without varying from the basicscope of the invention.

Oval System Configuration

FIGS. 20A-B illustrate another embodiment of the cluster tool 10 inwhich the processing chambers contained in the various processing racks,shown in FIGS. 4A-K (e.g., front end processing rack 52, the firstcentral processing rack 152, etc.), are not oriented in a linear fashionbut are arranged around a common central point in the system. Onedrawback of the linear orientation of the chambers is that the top-mostand bottom-most positions in a processing rack can be difficult for therobot to reach or requires a larger robot with greater arm extension tofully utilize all of the available space. This problem is especiallyproblematic where the 6-axis articulated robots are used since theirreach is limited by the distance from a central point. The problembecomes more pronounced where the chamber is at the top and at the endof a linearly arranged rack since these chambers are the farthestdistance from the robot center. Any chamber that is out of the reach ofthe robot cannot be accessed, so the processing rack height in somecases may not be fully utilized. This problem thus necessitatesadditional chambers and/or robots to access these chambers, whichincreases the cost and footprint of the tool.

In one embodiment, as shown in FIG. 20A, an alternative orientation maybe used to allow robot to access the process chambers which may beconsidered an oval shape or hemispherical shape. FIG. 20A is a side viewof an oval cluster tool configuration where a robot R1 is able to accessthe process chambers (labeled PM1-12) that are in a hemispherical shape.In this configuration the top-most and bottom-most stations in thecorner stacks can be moved in toward the center of the track, furtherreducing the distance the robot needs to move to service them. In thiscase, the corner stacks are cascaded in a staircase pattern from centerto top and from center to bottom. The result is that a smaller robotwith less reach can be used and the reduced reach distances will lowerthe robot handling times.

FIG. 20B illustrates an isometric view of one embodiment of a pluralityof vertically spaced processing chambers (labeled PM1-18) are arrangedabout a center point of the robot (labeled R1). This configuration takesadvantage of the spherical work area provided by a 6-axis articulatedrobot by bringing the “corner” stacks closer to the center of the track,making them easier for the robot to reach.

In one aspect of the invention, the configurations illustrated in FIGS.20A and 20B are merged to form a complete spherical, partial sphericalor hemispherical orientation of the processing chambers surrounding therobot to reduce the distance the robot needs to move to service theprocessing chambers and reduce the transfer time between processingchambers.

Gantry Robot Design Configuration

FIGS. 21A-D illustrate another embodiment of the cluster tool 10 whichuses multiple robots that are configured in a parallel processingconfiguration around the various processing racks so that a desiredprocessing sequence can be performed. In one embodiment, the parallelprocessing configuration contains three robots (items 420, 430 and 450shown in FIG. 21B) that move in vertical (hereafter defined as thez-direction) and parallel directions to access the various processingchambers retained in the processing racks aligned along the paralleldirection. One advantage of this system configuration is that if one ofthe robots in the central region 425 breaks or is taken down forservicing the system can still continue to process substrates using theother two robots. Another advantage of this configuration is theflexible and modular architecture allows the user to configure thenumber of processing chambers, processing racks, and processing robotsrequired to meet the throughput needs of the user.

FIG. 21A is an isometric view that illustrates an embodiment of thecluster tool 10 which contains three robots that are adapted to accessthe various process chambers that are stacked vertically in a firstprocessing rack 460 and a second processing rack 480. A stepper/scanner5 which is typically attached to the rear region 445 is not shown inFIG. 21A.

FIGS. 21B-C are plan and side views of the embodiment of the clustertool 10 shown in FIG. 21A. FIGS. 21A-C are intended to illustrate someof the various robot and process chamber configurations that may be usedin conjunction with this embodiment. In this configuration the clustertool 10 will generally contain a front end region 405, a central region425 and a rear region 445. The front end region 405 generally containsone or more pod assemblies 105 and a front end robot 410. The one ormore pod assemblies 105, or FOUPs, are generally adapted to accept oneor more cassettes 106 that may contain one or more substrates “W”, orwafers, that are to be processed in the cluster tool 10. The centralregion 425 generally contains a first central robot 420, a secondcentral robot 430, a third central robot 440, a first processing rack460 and a second processing rack 480. The first processing rack 460 anda second processing rack 480 contain various processing chambers (e.g.,coater/developer chamber 60, bake chamber 90, chill chamber 80, etc.)that are adapted to perform the various processing steps found in thesubstrate processing sequence. The front end robot 410 is adapted totransfer substrates between a cassette mounted in a pod assembly 105 andthe one or more processing chambers in the first processing racks 460 ora second processing rack 480 that abuts the front end region 405.

The first central robot 420, the second central robot 430, and the thirdcentral robot 440 are adapted to transfer substrates to the variousprocessing chambers contained in the first processing rack 460 and thesecond processing rack 480. In one embodiment, the second central robot430 is adapted to transfer substrates between the first processing rack460 and the second processing rack 480.

Referring to FIG. 21B, in one aspect of the invention the first centralrobot 420 is adapted to access the processing chambers in the firstprocessing rack 460 from at least one side, e.g., the first side 471, asshown. In another aspect, the second central robot 430 is adapted toaccess the processing chambers in the first processing rack 460 from atleast one side, and the second processing rack 480 from at least oneside, e.g., the second side 472 of the first processing rack and thefirst side 473 of the second processing rack 480. In one aspect, thethird central robot 450 is adapted to access the processing chambers inthe second processing rack 480 from at least one side, e.g., the secondside 474, as shown. In one aspect, the first side 471 of the firstprocessing rack 460, the second side 472 of the first processing rack460, the first side 473 of the second processing rack 480 and the secondside 474 of the second processing rack 480 are all aligned along adirection parallel to the horizontal motion assembly 490 (describedbelow) of each of the various robot assemblies (i.e., first centralrobot 420, second central robot 430, third central robot 450).

In one embodiment, the rear region 445 contains a rear robot 440 whichis adapted to transfer substrates between the processing chambersretained in the first processing racks 460 and a second processing rack480 that abut the rear region 445 and a stepper/scanner 5.

FIG. 21D illustrates a side view of one embodiment of the firstprocessing rack 460 as viewed when facing the first processing rack 460while standing on the side closest to the third central robot 440, andthus will coincide with the views shown in FIGS. 21A-C. The firstprocessing rack 460 will generally contain one or more coater/developerchambers 60, one or more chill chambers 80, one or more bake chambers90, one or more OEBR chambers 62, one or more PEB chambers 130, one ormore support chambers 65, and/or one or more HMDS chambers 70. In oneembodiment, as shown in FIG. 21D, the first processing rack 460 containseight coater/developer chambers 60 (labeled CD1-8), eighteen chillchambers 80 (labeled C1-18), eight bake chambers 90 (labeled B1-8), sixPEB chambers 130 (labeled PEB1-6), two OEBR chambers 62 (labeled 62)and/or six HMDS process chambers 70 (labeled P1-6).

FIG. 21E illustrates a side view of one embodiment of the secondprocessing rack 480 as viewed when facing the second processing rack 480while standing on the side closest to the third central robot 440, andthus will coincide with the views shown in FIGS. 21A-C. The secondprocessing rack 480 will generally contain one or more coater/developerchambers 60, one or more chill chambers 80, one or more bake chambers90, one or more OEBR chambers 62, one or more PEB chambers 130, one ormore support chambers 65, and/or one or more HMDS chambers 70. In oneembodiment, as shown in FIG. 21E, the second processing rack 480contains four coater/developer chambers 60 (labeled CD1-4), twenty fourchill chambers 80 (labeled C1-24), twelve bake chambers 90 (labeledB1-12), six PEB chambers 130 (labeled PEB1-6) and/or six supportchambers 65 (labeled S1-6).

The orientation, positioning and number of process chambers shown in theFIGS. 21A-E are not intended to be limiting as to the scope of theinvention, but are intended to illustrate the various embodiments of theinvention.

FIG. 21F illustrates the processing steps which each of the cluster toolrobots will service in the completion of the method steps 501, shown inFIG. 3A, using the cluster tool configuration illustrated in FIGS.21A-D. The method steps 508A, 510, 550 and 508B enclosed in the boxlabeled “A” are serviced by the front end robot 410. In one embodiment,the BARC coat step 510 is completed in a coater chamber 60A mounted inthe first processing rack 460 that abuts the front end region 405.Referring to FIGS. 21B, 21D and 21F, the front end robot 410 removes asubstrate from a pod assembly 105 and places the substrate in one of thecoater chambers 60A labeled CD1 or CD2 in the first processing rack 460.In another embodiment, the BARC coat step 510 is completed in a coaterchamber 60A mounted in the first processing rack 460 or the secondprocessing rack 480 that abuts the front end region 405. In thisembodiment, the develop step 550 may completed in a chill chamber 80mounted in the second processing rack 480 that abuts the front endregion 405.

In one embodiment, the process of transferring substrates between themethod steps 510 through 536, which are enclosed in the broken linelabeled “B”, are completed using the first central robot 420 and thesecond central robot 430 and the chambers contained in the firstprocessing rack 460. In another embodiment, the second central robot 430may be used to transfer the substrates to and from the first processingrack 460 and the second processing rack 480 so that available chambersin these racks can be used as required to meet the process sequencerequirements.

In one embodiment, the process of transferring substrates between theprocessing steps 536 through 550, which are enclosed in the box labeled“C”, are completed using the rear robot 450. In one embodiment, the OEBRstep 536 is completed in a OEBR chamber 62 mounted in the firstprocessing rack 460 that abuts the rear region 445. Referring to FIGS.21B and 21D, the rear robot 450 removes a substrate from OEBR chamber 62and exchanges the substrate in the stepper/scanner 5 where the exposurestep 538 is completed. After completing the exposure step 538 the rearrobot 450 removes the substrate from stepper/scanner 5 and places thesubstrate in one of the PEB chambers labeled PEB1-6 contained in thefirst processing rack 460 or the second processing rack 480.

In one embodiment, the process of transferring substrates between theprocessing steps 540 through 550, which are enclosed in the box labeled“D”, are completed using the second central robot 430 and the thirdrobot 440, and the chambers contained in the second processing rack 480.In another embodiment, the second central robot 430 may be used totransfer the substrates to and from the first processing rack 460 andthe second processing rack 480 so that available chambers in these rackscan be used as required to meet the process sequence requirements.

Referring to FIGS. 21B, 21D and 21F, after completing the process step550 the front end robot 410 then removes the substrate from one of thedeveloper chambers labeled CD1 or CD2 and place the substrate in itsrespective pod assembly 105.

FIG. 21G illustrates an embodiment of a robot assembly 411 that may beadapted for use as the front end robot 410, the first central robot 420,the second central robot 430, the third central robot 440 and/or therear robot 450. The robot assembly 411 generally contains a robothardware assembly 485, a horizontal motion assembly 490 and two verticalmotion assemblies 495. The robot hardware assembly 485 generallycontains a conventional selectively compliant articulated robot arm(SCARA) robot containing two independently controllable arms/blades. Inanother embodiment, as shown in FIG. 21H, a single blade type robothardware assembly 485 is used to transfer substrates. A dual blade robotmay be advantageous, for example, where the robot has to remove asubstrate from a processing chamber prior to placing the next substratein the same processing chamber. An exemplary dual bladed robot may bepurchased from Asyst Technologies in Fremont, Calif.

In one embodiment of the cluster tool 10, the front end robot 410, thefirst central robot 420, the second central robot 430, the third centralrobot 440 and/or the rear robot 450 may be adapted to transfersubstrates in groups of two or more to improve the system throughput byparallel processing the substrates. For example, in one aspect, a robotcontaining multiple independently controllable arms/blades is used topick up a plurality of substrates from a plurality of processingchambers and then transfer and deposit the substrates in a plurality ofsubsequent processing chambers. In one aspect, the robot is adapted topick-up or drop off simultaneously using an arm that has multiple bladesthat are spaced a desired distance, or pitch, apart. For example, thefront end robot 410, the first central robot 420, the second centralrobot 430, the third central robot 440 and/or the rear robot 450 mayhave a pair of blade assemblies 715A and 715B mounted on a support 720(shown in FIGS. 16A-B) that is attached to an end of a SCARA robot'sindependently controllable arms/blades. In another aspect, the robot isadapted to separately pick-up, transfer and drop off multiplesubstrates. For example, a two arm robot is adapted to pick-up asubstrate using a first arm, or blade, from a first chamber and thenmove to second processing chamber to pick-up a substrate using a secondarm, or blade, so that they can be transferred and dropped off in agroup.

Referring to FIGS. 21G-I, the horizontal motion assembly 490 generallycontains an enclosure 491, a robot actuator 489, a robot supportinterface 487, a linear slide 488 and cable guide assembly 492. Thelinear slide 488 may contain one or more linear ball bearing slides, ora conventional linear guide, that guides the robot support interface 487(e.g., robot base interface) and robot hardware assembly 485 as ittransfers the substrates between the various processing chambers. In oneembodiment, the robot actuator 489 is a direct drive linear brushlessservomotor, illustrated in FIG. 21I, which is adapted to move the robotsupport interface 487 relative to the linear slide 488 mounted on thesupport structure 486 of the enclosure 491. FIG. 21H illustrates oneembodiment of the horizontal motion assembly 490 in which a motor 489A(e.g., DC servo motor, stepper motor, etc.), a belt (not shown) andpulley system (not shown) which runs horizontally along the length ofthe horizontal motion assembly 490, are adapted to transfer and positionthe robot support interface 487 so that substrates can be transferredbetween the processing chambers.

FIG. 21H illustrates an isometric view of an embodiment of a robotassembly 411 shown in FIG. 21G that is intended to illustrate theinternal components contained in the horizontal motion assembly 490 andvertical motion assemblies 495. The vertical motion assembly 495generally contains a lift rail assembly 495A, a lift actuator 495B, anda vertical enclosure 495D (see FIG. 21G, not shown in FIG. 21H). Thelift rail assembly 495A contains a structural support 496 and a guidemechanism 494 to precisely raise and lower the horizontal motionassembly 490. The structural support 496 is a conventional structuralmember, such as an I-beam or other common structural component, that isdesigned to connect the robot assembly 411 to a frame member (not shown)in the cluster tool 10 and support the weight and loads created by thevertical motion assembly 495 and the horizontal motion assembly 490components. The guide mechanism 494 may be a linear ball bearing slideor a conventional linear guide that is able to align and precisely guidethe horizontal motion assembly 490 as it moves vertically along theguide mechanism 494.

Referring to FIG. 21H, in one embodiment of the vertical motion assembly495, the lift actuator 495B contains a motor 495C (e.g., DC servomotor,stepper motor, or other type of actuator) that is used in conjunctionwith a belt and pulley configuration (not shown) to raise and lower thehorizontal motion assembly 490 and its components. In another embodimentof the vertical motion assembly 495 (not shown), the lift actuator 495Bis a direct drive linear brushless servomotor that may be purchased fromDanaher Motion of Wood Dale, Ill. In one embodiment of the robotassembly 411, each vertical motion assembly contains a lift actuator495B to raise and lower the horizontal motion assembly 490 and othersupporting components. In another embodiment of the robot assembly 411,a single lift actuator 495B mounted to one of the two vertical motionassemblies 495 and the other vertical motion assembly 495 only containsthe guiding mechanism 494.

FIG. 21I illustrates an isometric view of one embodiment of theenclosure 491 contained in the horizontal motion assembly 490. Theenclosure 491 is adapted to cover and support the components in thehorizontal motion assembly 490, for safety and contamination reductionreasons. Since particle generation is commonly generated by mechanicalcomponents that roll, slide, or contact each other, it is important toassure that the components in the horizontal motion assembly 490, andalso the vertical motion assembly 495, do not cause defects on thesubstrates while the substrates are transferred through the clustertool. The enclosure 491 generally contains a plurality of walls (seeitems 491A-F) and a support structure 486, which form an enclosed regionthat minimizes the chance that generated particles inside the enclosurecan make their way to the surface of a substrate. The support structure486 is a structural member to which the walls 491A-F, robot actuator489, robot hardware assembly 485, and linear slides 488 all attach.

The fan unit 493 is adapted to draw air from inside the enclosure 491through a fan port 491G formed in one of the walls of the enclosure 491and pushes the particulate containing air through a filter (not shown)to remove particles before it is exhausted (see item “A”) into thecluster tool 10. In this configuration a fan 493A, contained in the fanunit 493, is designed to create a negative pressure inside the enclosure491 so that air outside the enclosure is drawn into the enclosure thuslimiting the possibility of particles generated inside the enclosure 491from leaking out. In one embodiment, the filter (not shown) is a HEPAtype filter or other type of filter that can remove the generatedparticulates from the air. The configuration shown in FIG. 21Iillustrates an embodiment where there are three fan units 493 that areused to draw air from the enclosure. In another embodiment, a single ordual fan unit system may be used in place of a three fan unit 493configuration, as shown, without varying form the scope of theinvention.

In one embodiment of the lift rail assembly 495A, a fan unit 493 (notshown) is adapted to draw air from inside each of the verticalenclosures 495D to minimize the chance that the particles generatedinside the vertical motion assembly 495 will cause defects on thedevices formed on the surface of the substrate.

Substrate Center Finding Device

In an effort to be more competitive in the market place and thus reduceCoO, electronic device manufacturers often spend a large amount of timetrying to improve the system uptime and system reliability to reducesubstrate scrap and increase the total system throughput (i.e., wafersstarts per week). One factor that can affect the system uptime andreliability is the misplacement of substrates in the various processingchambers which can cause substrate damage (e.g., chipping, substratebreakage, etc.). Damage to the substrates will cause the user to shutdown the current process, scrap all of the partially processedsubstrates, clean the affected chamber(s) and then restart the processsequence, all leading to significant system downtime and cost.Typically, to prevent substrate to substrate process variation anddamage to the substrate caused by misalignment of the substrate in oneof the processing chambers, or other chambers, the robot is repeatedlycalibrated to pick up and drop off a substrate from a transfer position.The transfer position may be, for example, the center point between theprocess chamber lift pins or the center point of the chuck.

To solve these problems, in one embodiment of the cluster tool 10, asubstrate position error detection and correction system 1200 (hereafterSPEDAC 1200), shown in FIG. 22A, is used. FIG. 22A illustrates anisometric view of two adjacent process chambers 1220 (e.g., bake chamber90, chill chamber 80, coater/developer chamber 60, etc.) retained in aprocessing rack that have two separate substrate position errordetection and correction systems 1200 mounted outside each of theiropenings 88. FIG. 22A illustrates one embodiment of the SPEDAC system1200 in which the transmitters 1206 are mounted to a top support 1204and the detectors 1205 are mounted n a bottom support 1203 which are allconnected to the process chamber 1220.

The SPEDAC system 1200 determines the presence of a substrate on asubstrate transport robot blade as it enters or exits the opening 88found in the various processing chambers and corrects for any error byrepositioning the robot blade 1210 in subsequent transferring steps. TheSPEDAC system 1200 utilizes a pair of beams (item “A”) sent from twopairs of transmitters 1206 to detectors 1205 to detect the position ofthe substrate as it passes through the beams and adjusts the robotposition to compensate for any error in the substrate's position. When asubstrate position error is detected, the system determines the extentof the misalignment and corrects such misalignment, if correctable, bythe movement of the robot blade position or alerts an operator foroperator intervention. Further description of an exemplary method ofdetecting and compensating for substrate misplacement on the blade ofthe robot is further described in U.S. Pat. No. 5,563,798, entitled“Wafer Positioning System,” issued Oct. 8, 1996, U.S. Pat. No.5,483,138, entitled “System and Method for Automated Positioning of aSubstrate in a Processing Chamber,” issued Jan. 9, 1996, and U.S. Pat.No. 5,980,194, issued Nov. 9, 1999, to Freerks, et al., which areincorporated by reference in their entirety to the extent notinconsistent with the present disclosure. An example of an exemplarymethod to control robot position and thus substrate position is furtherdescribed in U.S. Pat. No. 6,556,887, issued Apr. 29, 2003 to Freeman,et al., which is incorporated by reference in their entirety to theextent not inconsistent with the present disclosure.

Global Positioning

Another embodiment which may be used to improve the system uptime andsystem reliability by preventing substrate damage (e.g., chipping,substrate breakage) is the use of global positioning system (GPS) (notshown) to track and correct errors in the position of the robot bladeand/or the position of the substrate. In this configuration, the globalpositioning detection system is used to define the location of the robotblade (substrate or robot end effector) with respect to a predeterminedsystem datum. Typically, positional feedback of the robot blade'sposition is provided by incorporating encoders on shafts of drive motorsfor each control axis, that report the position of the motor and not theactual position of the robot blade. The actual position may vary fromthe reported position due to a loose coupling between the various drivecomponents, improper robot parameter setup, robot positional controldrift, undetected motion failures, and hardware collisions that mayoccur. Therefore, to resolve these issues, embodiments of the inventioncan be used to track the actual position of the robot blade, and thussubstrate position. In one embodiment, a global positioning device 1300and a communicating system (e.g., RF transmitter 1302, cable, etc.) isintegrated into the robot blade or robot to measure and feedback itsposition to the system controller 101. Therefore, by use of previouslycollected 3-dimensional coordinate system measurements of each transferposition, using the GPS sensor or other device, the system controllercan correct errors in the blade position by adjusting the position ofthe various robot parts. The robot parts are positioned by use ofconventional control means which may include encoders and other devicesfeedback type device used to control the robot's position.

In one embodiment, real-time positional feedback of the blade positioncan be accomplished by the communication of the global positioningdevice 1300 which is in communication with a RF transmitter 1302 mountednear the robot blade, that is in communication with an RF receiver 1303that communicates with the system controller 101. The feedback of theglobal positioning device 1300 allows the actual position of the robotblade to be compared to the commanded position eliminating positionaldrifting and failures due to undetected hardware failures,

In one embodiment, the system controller 101 uses the GPS system and theSPEDAC system 1200 (described above) to correct the robot positionalplacement and also the substrate to robot blade misalignment errors.This embodiment thus can be used to correct for substrate placementerrors or movement of the substrate relative to the robot blade.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A cluster tool for processing a substrate, comprising: a firstprocessing rack that comprises two or more groups of two or moresubstrate processing chambers that are stacked in a vertical direction,wherein the two or more substrate processing chambers in the two or moregroups have a first side and a second side that are aligned along afirst direction to access the substrate processing chamberstherethrough; a first robot assembly positioned adjacent to the firstprocessing rack and is adapted to transfer a substrate to the substrateprocessing chambers in the first processing rack from the first side,wherein the first robot assembly comprises: a robot that is adapted toposition a substrate at one or more points generally contained within ahorizontal plane; a vertical motion assembly having a vertical actuatorassembly that is adapted to position the robot in a direction generallyparallel to the vertical direction; and a horizontal motion assemblyhaving a motor that is adapted to position the robot in a directiongenerally parallel to the first direction; and a second robot assemblypositioned adjacent to the first processing rack and is adapted totransfer a substrate to the substrate processing chambers in the firstprocessing rack from the second side, wherein the second robot assemblycomprises: a robot that is adapted to position a substrate at one ormore points generally contained within a horizontal plane; a verticalmotion assembly having a vertical actuator assembly that is adapted toposition the robot in a direction generally parallel to the verticaldirection; and a horizontal motion assembly having a motor that isadapted to position the robot in a direction generally parallel to thefirst direction.
 2. The cluster tool of claim 1, further comprising: asecond processing rack that comprises two or more groups of two or moregroups of two or more substrate processing chambers that are stacked ina vertical direction, wherein the two or more substrate processingchambers in the two or more groups have a first side and a second sidethat are aligned along the first direction to access the substrateprocessing chambers therethrough; the second robot assembly ispositioned between the first processing rack and the second processingrack and is adapted to transfer a substrate to the substrate processingchambers in the first processing rack from the second side and transfera substrate to the substrate processing chambers in the secondprocessing rack from the first side; a third robot assembly positionedadjacent to the second processing rack and is adapted to transfer asubstrate to the substrate processing chambers in the second processingrack from the second side, wherein the third robot assembly comprises: arobot that is adapted to position a substrate at one or more pointsgenerally contained within a horizontal plane; a vertical motionassembly having a vertical actuator assembly that is adapted to positionthe robot in a direction generally parallel to the vertical direction;and a horizontal motion assembly having a motor that is adapted toposition the robot in a direction generally parallel to the firstdirection; and a fourth robot assembly that is adapted to transfer asubstrate to the substrate processing chambers in the first processingrack and the substrate processing chambers in the second processingrack, wherein the fourth robot assembly comprises: a robot that isadapted to position a substrate at one or more points generallycontained within a horizontal plane; a vertical motion assembly having avertical actuator assembly that is adapted to position the robot in adirection generally parallel to the vertical direction; and a horizontalmotion assembly having a motor that is adapted to position the robot ina direction generally perpendicular to the first direction.
 3. Thecluster tool of claim 1, wherein the horizontal motion assembly in thefirst robot assembly and the second robot assembly each furthercomprise: one or more walls that form an interior region in which themotor is enclosed; and one or more fan assemblies that are in fluidcommunication with the interior region, wherein the one or more fanassemblies are adapted to create a subatmospheric pressure in theinterior region.
 4. The cluster tool of claim 2, further comprising acassette that is adapted to retain two or more substrates; and a fifthrobot assembly that is adapted to position a substrate in the firstprocessing rack, position a substrate in a processing chamber in thesecond processing rack, and position a substrate in the cassette.
 5. Thecluster tool of claim 3, wherein the horizontal motion assembly furthercomprises a filter, wherein creating a subatmospheric pressure in theinterior region comprises drawing air from the internal region throughthe filter.
 6. The cluster tool of claim 3, wherein the horizontalmotion assembly further comprises a slide assembly that is disposed inthe interior region.
 7. The cluster tool of claim 1, wherein thevertical motion assembly in the first robot assembly and the secondrobot assembly each further comprise: one or more walls that enclose aninterior region; a lift rail assembly disposed in the interior region;and one or more fan assemblies that are in fluid communication with theinterior region, wherein the one or more fan assemblies are adapted tocreate a subatmospheric pressure in the interior region.